Evaporator removal / replacement DIY R129 - PeachParts Mercedes-Benz Forum

a2aa · #1 08-28-2012, 10:37 AM

Below is a transcript on how I replaced my 1994 SL500 R129 evaporator back in 2000. I want to make sure that I share it to all you Mercedes DIY enthusiasts. Good luck!

R129 Evaporator removal
I
• pull top down
• back seats up to max
• extend steering wheel out and down max
• put shift knob to N position
II
• remove driver’s bolster
• remove center vents by pulling cover and access screws – gently pull and disconnect wires –label
• remove small glove compartment be careful not to break plastic extension used to open the compartment
• Disconnect battery
• from access below driver’s side where bolster was in, reach up behind the instrument cluster then push gently on the housing and work cluster out on this side while also accessing the opening on the center vent area, push on the right side of the instrument cluster until it comes out.
• Disconnect and label.

III
• With the use of “radio pulls”, remove radio, connections and mark them
• Remove screw from black lining of the misc./coin compartment w/c has the slow-open door, then remove retaining screws right under the black lining label screws and lining together.
• Gently lift wood panel from the window switches area, then pull the panel out.
IV
• Steering wheel : remove torx screw behind wheels using T25. Upon removing the airbag, release all connections & label. Use an allen bolt to release the main bolt holding the steering wheel. I would suggest pneumatic (air tool) due to torque requirement to release it. DO NOT PUSH AGAINST THE STEARING LOCK TO REMOVE THE MAIN BOLT-YOU WILL BEAK THE LOCK AND YOUR COST WILL GO UP. Note alignment before taking the wheel off. Secure in a dry area.
• Passenger airbag: I rate this very hard due to access to the bolt holding the airbag. With the airbag in place, you can’t remove the bolster screws under it. Use an open 8mm open wrench and feel for the screws that are holding the bolster. Might need to pull on bolter down ward( be careful not the crack the housing). Remove the airbag using 10 mm socket secure and label.
• Dash board: when all screws are taken off, attempt to remove the dash. Don’t force it out. It will interfere with the cruise control lever and the ignition key. Need a 2nd person to help remove the dash.
• Blower motor: Remove wiper assembly and mark connections then remove the “vent-looking” supports attached to the lower part of the windshield. Remove the air filter housing. (Make sure you don’t accidentally drop anything in air inlet tube. Unbolt the housing by accessing the upper portion of the firewall near the engine.
V
• **Remove support brace (black) and be sure NOT to jack the car up or else the windshield will crack!!!*** LABEL
• Heater/evaporator core: Numerous connections are going to the box, so label them. Unplug all necessary vacuum connections. Secure all screws and mark them. There are 4 screw holding box.
• Heater hose/ expansion valve: Drain coolant.
Disconnect all the connecting aluminum heater hoses on the engine compartment side and from the heater core side and leave these hoses in the car. Recover refrigerant and release expansion valve.
Allen and 8mm socket needed ** COVER A/C connections with duck tape to avoid moisture contamination**
**Remove core box**
• Vacuum Actuators: There are actually 7 vacuum actuators on the box. I suggest that you replace all of them. Mark actuators themselves and location of such actuator with same markings to secure and prevent mistakes. Replace each and label accordingly. Keep old ones for stock and future reference. You have some actuators on the blower motor side that might need replacing and you would have extra ones to experiment with before purchasing new ones-if they go out.
• Drain hose: Replace the drain tubes with your choice of either clear tubing or rigid radiator hose type tubing of the correct size. Make sure it’s kink free to prevent “flooding” the interior of your car.
• Heater Core: Remove the core and test fit replacement core. **REPLACE O-RINGS**on all connections that require one. Clean box and install new heater core.
• Evaporator: Well, this is the reason for all this work so lets make sure we do this right. Release the cover to the evaporator. ** MEASURE THE AMOUNT OF REFRGERANT OIL THAT YOU DRAIN FROM THE EVAP AND NOTE IT. ** Sit the new evap to the old one for size and fit comparison before actually putting it in the housing. ** REPLACE O-RINGS {green} WITH CORRECT SIZE AND LUBE THEM WITH NYLOG DESIGNATED FOR 134 A REFRIGERANT** Oil requirement is PAG46 ( low viscosity)
**1) Also, I have noticed that the evaporator box mounting screws @ the bottom of the box, right under the area where the supposed leak started has a lot of corrosion(rust) forming on it. Whether the leak caused this bolt to rust or vise-versa is unknown. I went ahead and coated the headbolts with POR65 and painted it with clear paint.
**2) I replaced the foam pad surrounding the opening of the evap box that butts on the firewall. Mine was sticky and mushy. It’s -/+ ½ “thick and 1/3” deep foam padding with one side adhesive peal off backing.
Recommended amt : Recommended amt of oil for evaporator replacement is 40cc. (as per ALLDATADIY) cap off the evaporator to prevent moisture from contaminating the system. Pag 46 refrigerant oil is hydroscopic and will eat up aluminum if contaminated with water or moisture.
VI
• Before attempting to return the box, look for all possible unmarked connections and make sure they are marked (vacuum and electrical).
• ** Detach the top vent attachment of the box mark L/R then remove the rubber seals that are on the fire wall that houses the aluminum heater tubes. Don’t attach the aluminum tubes to the heater core – the box won’t fit!!
• Once the box is roughly in place, make sure that the evaporator connections are not being damaged while box is being situated.
• Attach the aluminum heater connections to the heater core with new o-rings. After cleaning the ends of the tubing, slip the tubes through the firewall and secure the rubber insulation and be careful not to bend or kink the tubes- you will have to replace them if you do due to risk of future failure of the damaged area.
• Attach the exp. valve and tighten to +/- 8Nm of torque to the 8 mm bolt. Make sure that insulation is in place to prevent moisture from entering the cabin.
• ** I had to use the old bracket that would hold the copper tubes in place due to the new bracket is not compatible with the allen screws that would hold the expansion valve to the evaporator connections. After grinding the opening of the bracket, it fit the new diameters of the copper tubing perfectly.
• After installing the box and tightening the connections, remove the rcvr/drier and install new unit with new o-rings laced with Nylog lubricant. I used the old pressure switches. I don’t think that there is anything wrong with them. And if there is, the gauges will tell me and they are easy to access and replace.
• Attach vacuum pump and vacuum down to -29 for about 120 mins.
• IF the system retains vacuum, start charge. Attach the 12 oz bottle to the yellow (middle) line and purge the line so air won’t be pushed inside the system. Attach the low and high sides. With the bottle open, open both low and high side and let the bottle get sucked in the system. When the bottle stops charging, shut HI side gauge and start the car, continue to charge only the low side until gauges read normal value or vent temps reach their expected values. Disconnect when values are reached. Never invert or shake the bottle while charging. The liquid form of the refrigerant might damage the compressor seals. Remember that the compressor can compress air, not liquid. If the bottle quits charging the system, dip the can in a warm water basin~ 110 degrees. Warm- NEVER HOT. This will convert the liquid form to gas thus increasing pressure of the can. This will then push the refrigerant into the system faster.
• ** BEFORE STARTING THE CAR, MAKE SURE THAT THE AIRBAGS ARE CONNECTED TO PREVENT ERROR MESSAGES THAT YOU’D NEED THE DEALERSHIP TO RESET**
• After 20 mins, check for leaks via UV light. If none, continue in assembling the rest of the interior dash and electrical connections of the car.
• You are almost done with this project—take your time. Rushing will make you pull on things are break them. Your “cost of repair” will go up. These brackets are not cheap if you break them.
• REFILL the radiator with coolant/water solution- here in Texas I use a 40% coolant and 60% water with XEREX G05. This has the same chemical composition as the MBZ brand. Autozone carries them @ $8/gal.
• Tighten all hose connections.
• Attach new drain hoses to the evaporator box by pushing it through from the bottom of the car- you definitely need some one to guide the hose in and aim it to attach to the drain connections at the bottom of the evap box. I used a rigid clear hose from my local hardware store. I got 2 ft and cut it in half. Pre heat the tube using a hair drier to soften the tube for easy insertion. Do not melt the tube. Once attached, tighten with zip ties then trim.
• Start and put fan speed to 2 (mid speed ) @ 56 degree setting and let the car idle. Note the ambient temp and the vent temp. Then note the pressures of the low and high side of the gauges. They should run around 30 for the low and 225 for the high with 93 degree ambient temperature. Vent temps should read ~ 48 degrees @ idle and recirc button ON.
• Turn off garage lights – if possible, then wear your yellow goggles and turn on UV light and inspect all connections to check for leaks- There will be a small amt of dye around the gauge connections due to small leakage when attaching and removing the gauges. THIS IS NORMAL.
• Aim the light to the expansion valve and receiver/drier area. There should be NO residue or dye around these areas.
• After 5 mins., there will be water coming out of the drain tubes below the car. Aim the light to the puddle and PRAY that you don’t see dye here. If none, all the components that you attached are all leak free!!!
• Sit back and enjoy the auxiliary fan kick in and out, watch the gauges.
• Test drive: Before driving the car, check all electronic components are in working condition. The radio will need the proper code to activate the unit. This code is available to you via dealership. You will need the last 8 digits of the VIN number. Keep this number for future resetting. Tighten the battery bolt.
• I suggest driving the car close to home for obvious reasons. After this, enjoy the car and brag like crazy THAT YOU DID IT YOURSELF!!

lee polowczuk · #2 08-28-2012, 11:23 AM

How many man hours did this take?

Quote:

Originally Posted by a2aa

Below is a transcript on how I replaced my 1994 SL500 R129 evaporator back in 2000. I want to make sure that I share it to all you Mercedes DIY enthusiasts. Good luck!

R129 Evaporator removal
I
• pull top down
• back seats up to max
• extend steering wheel out and down max
• put shift knob to N position
II
• remove driver’s bolster
• remove center vents by pulling cover and access screws – gently pull and disconnect wires –label
• remove small glove compartment be careful not to break plastic extension used to open the compartment
• Disconnect battery
• from access below driver’s side where bolster was in, reach up behind the instrument cluster then push gently on the housing and work cluster out on this side while also accessing the opening on the center vent area, push on the right side of the instrument cluster until it comes out.
• Disconnect and label.

III
• With the use of “radio pulls”, remove radio, connections and mark them
• Remove screw from black lining of the misc./coin compartment w/c has the slow-open door, then remove retaining screws right under the black lining label screws and lining together.
• Gently lift wood panel from the window switches area, then pull the panel out.
IV
• Steering wheel : remove torx screw behind wheels using T25. Upon removing the airbag, release all connections & label. Use an allen bolt to release the main bolt holding the steering wheel. I would suggest pneumatic (air tool) due to torque requirement to release it. DO NOT PUSH AGAINST THE STEARING LOCK TO REMOVE THE MAIN BOLT-YOU WILL BEAK THE LOCK AND YOUR COST WILL GO UP. Note alignment before taking the wheel off. Secure in a dry area.
• Passenger airbag: I rate this very hard due to access to the bolt holding the airbag. With the airbag in place, you can’t remove the bolster screws under it. Use an open 8mm open wrench and feel for the screws that are holding the bolster. Might need to pull on bolter down ward( be careful not the crack the housing). Remove the airbag using 10 mm socket secure and label.
• Dash board: when all screws are taken off, attempt to remove the dash. Don’t force it out. It will interfere with the cruise control lever and the ignition key. Need a 2nd person to help remove the dash.
• Blower motor: Remove wiper assembly and mark connections then remove the “vent-looking” supports attached to the lower part of the windshield. Remove the air filter housing. (Make sure you don’t accidentally drop anything in air inlet tube. Unbolt the housing by accessing the upper portion of the firewall near the engine.
V
• **Remove support brace (black) and be sure NOT to jack the car up or else the windshield will crack!!!*** LABEL
• Heater/evaporator core: Numerous connections are going to the box, so label them. Unplug all necessary vacuum connections. Secure all screws and mark them. There are 4 screw holding box.
• Heater hose/ expansion valve: Drain coolant.
Disconnect all the connecting aluminum heater hoses on the engine compartment side and from the heater core side and leave these hoses in the car. Recover refrigerant and release expansion valve.
Allen and 8mm socket needed ** COVER A/C connections with duck tape to avoid moisture contamination**
**Remove core box**
• Vacuum Actuators: There are actually 7 vacuum actuators on the box. I suggest that you replace all of them. Mark actuators themselves and location of such actuator with same markings to secure and prevent mistakes. Replace each and label accordingly. Keep old ones for stock and future reference. You have some actuators on the blower motor side that might need replacing and you would have extra ones to experiment with before purchasing new ones-if they go out.
• Drain hose: Replace the drain tubes with your choice of either clear tubing or rigid radiator hose type tubing of the correct size. Make sure it’s kink free to prevent “flooding” the interior of your car.
• Heater Core: Remove the core and test fit replacement core. **REPLACE O-RINGS**on all connections that require one. Clean box and install new heater core.
• Evaporator: Well, this is the reason for all this work so lets make sure we do this right. Release the cover to the evaporator. ** MEASURE THE AMOUNT OF REFRGERANT OIL THAT YOU DRAIN FROM THE EVAP AND NOTE IT. ** Sit the new evap to the old one for size and fit comparison before actually putting it in the housing. ** REPLACE O-RINGS {green} WITH CORRECT SIZE AND LUBE THEM WITH NYLOG DESIGNATED FOR 134 A REFRIGERANT** Oil requirement is PAG46 ( low viscosity)
**1) Also, I have noticed that the evaporator box mounting screws @ the bottom of the box, right under the area where the supposed leak started has a lot of corrosion(rust) forming on it. Whether the leak caused this bolt to rust or vise-versa is unknown. I went ahead and coated the headbolts with POR65 and painted it with clear paint.
**2) I replaced the foam pad surrounding the opening of the evap box that butts on the firewall. Mine was sticky and mushy. It’s -/+ ½ “thick and 1/3” deep foam padding with one side adhesive peal off backing.
Recommended amt : Recommended amt of oil for evaporator replacement is 40cc. (as per ALLDATADIY) cap off the evaporator to prevent moisture from contaminating the system. Pag 46 refrigerant oil is hydroscopic and will eat up aluminum if contaminated with water or moisture.
VI
• Before attempting to return the box, look for all possible unmarked connections and make sure they are marked (vacuum and electrical).
• ** Detach the top vent attachment of the box mark L/R then remove the rubber seals that are on the fire wall that houses the aluminum heater tubes. Don’t attach the aluminum tubes to the heater core – the box won’t fit!!
• Once the box is roughly in place, make sure that the evaporator connections are not being damaged while box is being situated.
• Attach the aluminum heater connections to the heater core with new o-rings. After cleaning the ends of the tubing, slip the tubes through the firewall and secure the rubber insulation and be careful not to bend or kink the tubes- you will have to replace them if you do due to risk of future failure of the damaged area.
• Attach the exp. valve and tighten to +/- 8Nm of torque to the 8 mm bolt. Make sure that insulation is in place to prevent moisture from entering the cabin.
• ** I had to use the old bracket that would hold the copper tubes in place due to the new bracket is not compatible with the allen screws that would hold the expansion valve to the evaporator connections. After grinding the opening of the bracket, it fit the new diameters of the copper tubing perfectly.
• After installing the box and tightening the connections, remove the rcvr/drier and install new unit with new o-rings laced with Nylog lubricant. I used the old pressure switches. I don’t think that there is anything wrong with them. And if there is, the gauges will tell me and they are easy to access and replace.
• Attach vacuum pump and vacuum down to -29 for about 120 mins.
• IF the system retains vacuum, start charge. Attach the 12 oz bottle to the yellow (middle) line and purge the line so air won’t be pushed inside the system. Attach the low and high sides. With the bottle open, open both low and high side and let the bottle get sucked in the system. When the bottle stops charging, shut HI side gauge and start the car, continue to charge only the low side until gauges read normal value or vent temps reach their expected values. Disconnect when values are reached. Never invert or shake the bottle while charging. The liquid form of the refrigerant might damage the compressor seals. Remember that the compressor can compress air, not liquid. If the bottle quits charging the system, dip the can in a warm water basin~ 110 degrees. Warm- NEVER HOT. This will convert the liquid form to gas thus increasing pressure of the can. This will then push the refrigerant into the system faster.
• ** BEFORE STARTING THE CAR, MAKE SURE THAT THE AIRBAGS ARE CONNECTED TO PREVENT ERROR MESSAGES THAT YOU’D NEED THE DEALERSHIP TO RESET**
• After 20 mins, check for leaks via UV light. If none, continue in assembling the rest of the interior dash and electrical connections of the car.
• You are almost done with this project—take your time. Rushing will make you pull on things are break them. Your “cost of repair” will go up. These brackets are not cheap if you break them.
• REFILL the radiator with coolant/water solution- here in Texas I use a 40% coolant and 60% water with XEREX G05. This has the same chemical composition as the MBZ brand. Autozone carries them @ $8/gal.
• Tighten all hose connections.
• Attach new drain hoses to the evaporator box by pushing it through from the bottom of the car- you definitely need some one to guide the hose in and aim it to attach to the drain connections at the bottom of the evap box. I used a rigid clear hose from my local hardware store. I got 2 ft and cut it in half. Pre heat the tube using a hair drier to soften the tube for easy insertion. Do not melt the tube. Once attached, tighten with zip ties then trim.
• Start and put fan speed to 2 (mid speed ) @ 56 degree setting and let the car idle. Note the ambient temp and the vent temp. Then note the pressures of the low and high side of the gauges. They should run around 30 for the low and 225 for the high with 93 degree ambient temperature. Vent temps should read ~ 48 degrees @ idle and recirc button ON.
• Turn off garage lights – if possible, then wear your yellow goggles and turn on UV light and inspect all connections to check for leaks- There will be a small amt of dye around the gauge connections due to small leakage when attaching and removing the gauges. THIS IS NORMAL.
• Aim the light to the expansion valve and receiver/drier area. There should be NO residue or dye around these areas.
• After 5 mins., there will be water coming out of the drain tubes below the car. Aim the light to the puddle and PRAY that you don’t see dye here. If none, all the components that you attached are all leak free!!!
• Sit back and enjoy the auxiliary fan kick in and out, watch the gauges.
• Test drive: Before driving the car, check all electronic components are in working condition. The radio will need the proper code to activate the unit. This code is available to you via dealership. You will need the last 8 digits of the VIN number. Keep this number for future resetting. Tighten the battery bolt.
• I suggest driving the car close to home for obvious reasons. After this, enjoy the car and brag like crazy THAT YOU DID IT YOURSELF!!

a2aa · #3 08-28-2012, 12:29 PM

The dealership qouted me 22 hrs. I finished in 26 hrs. (spread out in 7 days)

lee polowczuk · #4 08-28-2012, 02:53 PM

thanks...same as a 124