Hello: I purchased an R134a/R12 dual refrigerant recovery and recharge unit. I just changed the a/c pressure switch and drier in my car. The machine pulled and held a vacuum on the system. So, all of that is fine. However, I can't get the freon into my a/c system.

I'm using R134a because it had already been converted. I just want the a/c working now and will convert back to R12 later. The problem now is the "pressurizing tank" light on the unit keeps flashing. The manual states that I should start the car and turn on the a/c because there is a pressure difference that needs to be corrected. I did that and it is still the same.

The a/c compressor in m car is not turning on because there is no refrigerant in the system. It seems like I'm almost there, but I need that little push from the in house experts.

Thank you for your help.

I think I'm familiar with that unit. It will need to see 100PSI in the tank before it will charge. When it is "pressurizing tank" it is actually warming the tank which raises the pressure in the tank assuming it has sufficient refrigerant. It can take several minutes before pressure comes up. In addition there are valves inline and at the tank that need to be opened before use and ideally closed after every use. If the valves are closed it won't see the pressure and won't charge.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

Thanks for your response.

I pulled a vacuum on the car's a/c system and immediately set the unit to charge it with virgin R134. Seven ounces were sucked in rather quickly, then nothing. The virgin cylinder seemed to be heated pretty good. I don't know how hot it should get before the pressure is high enough. The manual says it could take 10 minutes, but it was longer than that.

The car's compressor doesn't seem to be turning on. The clutch certainly isn't turning, but I can turn it by hand. Does the car's compressor need to be running in order to draw in more of the refrigerant? If so, how do I get it to run?

I vacuumed and tried to charge the system again. The low side reads 105 and the high side is 110. The compressor is still not on. Six ounces of refrigerant were sucked into the system before it stopped. Any ideas?

search posts by larry bible.... he seems to know the systems...

there's a way to jump the a/c compressor to have it start up....

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1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


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from mb doc:

if you remove the klima & use a jumper wire between circuit 15(power) & 87(compressor) the compressor has to run....

Those circuits are marked on the relay..& are marked 5 & 7 on the electrical connector.

That test will allow you to decide if the compressor is good or if you are having "klima" control problems.
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__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

Thanks Lee. I was just doing that when I came in and saw your post. I jumped the pressure switch and the compressor turns on and the clutch engages. However, there still seems to be a pressure gradient. Maybe now that I know how to turn on the compressor I should evacuate the system, pull a vaccum and try to charge it again.

Oh, and I've read so many related a/c posts that my head hurts.

There's still a problem with the pressure as the "pressurizing tank" light on the a/c recovery/recharge unit continues flashing. The refrigerant is just not getting drawn into the car's a/c system. I didn't perform another evacuate and vacuum cycle after I got the car's compressor to turn on. I don't know if that's where my problem is.

So far only 8 ounces of refrigerant have gone in. I don't want to run the car's compressor too long without a sufficient charge.

Does anyone have any other recommendations?

what kind of air do you have when you run the compressor.....??? cool? i think the systems don't take much more than a can and a half or so..

i don't want to lead you down the wrong path...but wondering if you have a stuck expansion valve.

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

It doesn't feel cool yet. The system was totally empty as I evacuated it and drew a good vacuum on it for a while. I changed the switches and the drier. The specs call for 38.75 ounces of R134a in the system. So, 8 ounces isn't going to do much. I'm not negating your theory about the expansion valve, I'm just stating some facts.

Thank you.

ok.... the other thing is..anytime i have added refrigerant.. i have someone step on the gas and get the rpms up to 1500

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

Thank you.
I just tried that. Nothing.

This is what is written in the manual for the a/c recovery/recharge unit:

"In some instances a differential condition may occur. This happens when there is a pressure balance between the unit and the vehicle air conditioning system. If a differential condition is reached, the PRESSURIZING TANK light will begin flashing. To correct a differential condition, turn the engine on, start the vehicle air conditioning system and press START/STOP OPERATION on the left hand panel."

Well, I've done that and it still does not draw refrigerant into the system. I jumped the pressure switch to get the compressor to turn on and the clutch spins freely while it's on. It's not intermittent.

I really need to know how to get that pressure gradient taken care of. Do I need to evacuate the system and draw a vacuum again now that I have the compressor running?

with the equipment you have it should be a piece of cake.

headed to port st lucie to look at a 95 e320 coupe... will check back in later

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

So, you're saying I'm not the sharpest tool in the shed? If so, I'm sure you're mistaken as my wife says I pretty much know everything. Well, except how to operate an auto a/c recovery/recharge unit.