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  #1  
Old 04-29-2011, 07:31 PM
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84 190D A/C help!

My next task is to get my ac working, the compressor is not engaging. I plan on hooking up gauges to see what is going on, I think it has R12 in it. I have some R12 but dont want to waste it if I have a leak, is there a way to see if I have a leak without wasting my R12? Also what pressures should I see at the high and low sides? Thankyou.


Last edited by 04 Diesel; 05-01-2011 at 01:27 PM.
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Old 05-01-2011, 09:56 AM
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?? Anybody??
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Old 05-01-2011, 11:03 AM
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How about where is the low side? ( side where I add my r12) It is up top on the drivers side wheel well? (84 190D)
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Old 05-01-2011, 11:57 AM
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Hello.
a/c work is pretty simple overall, but you need a few tools. a set of gauges is very important.
the low side connection will be on the large line I usually find them near the firewall on MB's, but I'm not familiar with your car. between the firewall, and the compressor is the large line, and that's where the low side connector has to be.
the high side needs to be between the compressor and the front of the car, on the line that leads to the condenser.
if you still have R12 in your car, the caps will be brass, or plastic black... if they are colored red and blue, your car has been "converted"
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #5  
Old 05-01-2011, 12:05 PM
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when you attach the gauges, with the compressor off, the pressure should read around 100 psi if you do not have a leak.
more likely, it's going to either read 0 or really low. if it's reading low, there's a leak, and you have to pump it up with a dry gas to find the leak. I use nitrogen, but you can use co2, argon, helium etc. just NOT COMPRESSED AIR! if it's at 0 you need to add in a trace gas of 4oz R22 to use a electronic sniffer. you can also use soap bubbles and check all the fittings and connections with bubbles... not as reliable but it's helpful for spotting leaks in the o-rings.
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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Old 05-01-2011, 01:23 PM
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Originally Posted by vstech View Post
when you attach the gauges, with the compressor off, the pressure should read around 100 psi if you do not have a leak.
more likely, it's going to either read 0 or really low. if it's reading low, there's a leak, and you have to pump it up with a dry gas to find the leak. I use nitrogen, but you can use co2, argon, helium etc. just NOT COMPRESSED AIR! if it's at 0 you need to add in a trace gas of 4oz R22 to use a electronic sniffer. you can also use soap bubbles and check all the fittings and connections with bubbles... not as reliable but it's helpful for spotting leaks in the o-rings.

Ok, just hooked up gauge to low side with car off and I had 70 psi. Is that good? Maybe just need to add more R12?
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Old 05-01-2011, 01:39 PM
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Quote:
Originally Posted by 04 Diesel View Post
Ok, just hooked up gauge to low side with car off and I had 70 psi. Is that good? Maybe just need to add more R12?
How long had the AC system been turned off when you got that reading ?
There is the possibility you only need topping off with R12..

HOWEVER, you do not have enough info to do that yet...

You are going to need to check the vent temperatures with a pencil thermometer..about $5 ..... while making sure the test conditions are correct...
and then hook up the gauges to both the high and low sides and see what readings you get...

The specs for the test have been given lately.. from memory----.. one of the more important is having a good fan blowing right into your condensor.... and being at high idle, windows OPEN.... set on MAX AiR.... clean the condensor AND radiator fins ... of course this has to be done outside.... carbon monoxide from your exhaust is deadly in small amounts....

If you do not have the test conditions correct you will get junk for information from the gauges.... and waste money and potentially R12...
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Old 05-01-2011, 01:41 PM
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Originally Posted by leathermang View Post
How long had the AC system been turned off when you got that reading ?
There is the possibility you only need topping off with R12..

HOWEVER, you do not have enough info to do that yet...

You are going to need to check the vent temperatures with a pencil thermometer..about $5 ..... while making sure the test conditions are correct...
and then hook up the gauges to both the high and low sides and see what readings you get...

The specs for the test have been given lately.. from memory----.. one of the more important is having a good fan blowing right into your condensor.... and being at high idle, windows OPEN.... set on MAX AiR.... clean the condensor AND radiator fins ... of course this has to be done outside.... carbon monoxide from your exhaust is deadly in small amounts....

ac has not ran for almost a year, the compressor does not turn on.
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Old 05-01-2011, 01:43 PM
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The 70 lbs is sounding very good...

Why does the compressor not turn on ?

You need to tell us as much about the history and condition of the vehicle and AC system as you can...
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  #10  
Old 05-01-2011, 02:10 PM
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Originally Posted by leathermang View Post
The 70 lbs is sounding very good...

Why does the compressor not turn on ?

You need to tell us as much about the history and condition of the vehicle and AC system as you can...
I dont know why compressor is not turning on.
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  #11  
Old 05-01-2011, 02:51 PM
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Failing to answer all the questions posed by people trying to help is not a good strategy.
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  #12  
Old 05-01-2011, 03:15 PM
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lol

First thing to do is see if you can turn the "inside" portion of the wheel on the front of the compressor by hand with the car off. If it turns easily then jump 12v to the terminal at the compressor to see if it will come on with the engine running. If it does then it is either low on freon or there is some stuff going on with the controls.
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  #13  
Old 05-01-2011, 04:24 PM
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since you have 70 psi the compressor is not out due to pressure, it's likely low, but no way to know that until some temperature readings are done, and the system is running. next thing is to test the freeze switch. if it's bad, the compressor will not engage.
after that, it's time to test the CCU push button unit. you may need to pull it, and look for bad solder joints, or just resolder them all.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #14  
Old 05-01-2011, 06:53 PM
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Sorry, went to visit my daughter in the hospital, it is raining now so Ill try tomorrow. Thanks for all your help.

Last edited by 04 Diesel; 05-01-2011 at 08:06 PM.
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  #15  
Old 05-01-2011, 08:10 PM
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Quote:
Originally Posted by engatwork View Post
lol

First thing to do is see if you can turn the "inside" portion of the wheel on the front of the compressor by hand with the car off. If it turns easily then jump 12v to the terminal at the compressor to see if it will come on with the engine running. If it does then it is either low on freon or there is some stuff going on with the controls.
Yes I can turn the front of the compressor by hand, when I jump the compressor does the car have to be running? Very tight in there, dont want to get my hand caught in the belt.

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