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Unread 06-23-2013, 02:00 PM   #1
john126293
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Join Date: Sep 2012
Posts: 19
I have a 1996 jeep Cherokee I just added some freon and know my ac doesn't get cold at all it blew cool at 1st but not cold like it use to but when I added the freon it doesn't come out cool at all anybody know what could be wrong. The pressure on the low side was almost at 55 psi on the gauge after I added the freon

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Unread 06-23-2013, 02:48 PM   #2
AZ Jeff
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2014 JK Wrangler 
 
Join Date: Sep 2005
Location: San Tan Valley Arizona, AZ
Posts: 7,397
Ahhhh......another one of these threads. The proper method is thus:

On an R134a system, you CANNOT just "add refrigerant" based on low side pressures. There is a VERY fine line between "too much" refrigerant and "not enough". This is a MAJOR DIFFERENCE that was not the case with the old R12 systems, which were tolerant of a very wide range of charge levels.

You should measure temperatures and pressures on the system with a full charging manifold. High side pressure, low side pressure, ambient air temp, and vent temperature with fan on "ON".

Then come back and report what you find and we can coach you what to look for next.
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1992 XJ -- stock (RIP)
2000 XJ -- lots of basic mods. Sold to fellow forum member. I miss it.
2014 JK -- the project is just starting!
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Unread 07-01-2013, 05:33 PM   #3
jeepsrtoys
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1997 XJ Cherokee 
 
Join Date: Dec 2008
Location: indiana
Posts: 19
Ok, I am going to highjack this thread. So I have been looking through a couple A/C problem threads. I have a issue with mine. though I haven't added any Freon.
Things I know:
1. when the a/c is selected the compressor engages for about 5 seconds, then disengages for about 30 seconds then back on for 5 seconds and so on.. (the time it isn't engaged might be longer than 30 seconds, but at the end no cold air)
2. on the low pressure side I measure 55 psi. which might be a little high for it being 75 outside. but the system used to work, and I haven't added Freon.
3. when the compressor engages the system drops to almost 0 psi....

I don't completely understand the function of how a/c systems work.. but I would assume there is a blockage somewhere in the system.
I also would assume I need to check the psi on the high side and see if it goes up when the compressor engages.. ? or...?
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Unread 07-01-2013, 07:25 PM   #4
AZ Jeff
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2014 JK Wrangler 
 
Join Date: Sep 2005
Location: San Tan Valley Arizona, AZ
Posts: 7,397
Quote:
Originally Posted by jeepsrtoys View Post
Ok, I am going to highjack this thread. So I have been looking through a couple A/C problem threads. I have a issue with mine. though I haven't added any Freon.
....
3. when the compressor engages the system drops to almost 0 psi....

I don't completely understand the function of how a/c systems work.. but I would assume there is a blockage somewhere in the system.
I also would assume I need to check the psi on the high side and see if it goes up when the compressor engages.. ? or...?
You are measuring LOW SIDE pressures, also known as "Suction pressures". The fact that it goes to zero when the compressor kicks on indicates a low charge of refrigerant.

Since you are not experienced with AC systems, here is what I recommend for a low-cost/high-effectiveness solution:

1. take the vehicle to a COMPETENT AC shop. Have them diagnose the problem. They may need to add refrigerant to complete diagnosis.
2. Once they tell you what is wrong, repair/replace the defective parts yourself.
3. Once you have replaced the defective parts, take the vehicle back to the same shop, tell them what you did, and have them evacuate and recharge the unit.

It might help if you do some research on auto AC systems, such as:

http://auto.howstuffworks.com/automo...nditioning.htm
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1992 XJ -- stock (RIP)
2000 XJ -- lots of basic mods. Sold to fellow forum member. I miss it.
2014 JK -- the project is just starting!
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Unread 06-02-2014, 10:03 PM   #5
brigbeach
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1996 XJ Cherokee 
 
Join Date: May 2010
Location: brigantine, Brigantine, NJ
Posts: 222
Quote:
Originally Posted by AZ Jeff View Post
You are measuring LOW SIDE pressures, also known as "Suction pressures". The fact that it goes to zero when the compressor kicks on indicates a low charge of refrigerant.

Since you are not experienced with AC systems, here is what I recommend for a low-cost/high-effectiveness solution:

1. take the vehicle to a COMPETENT AC shop. Have them diagnose the problem. They may need to add refrigerant to complete diagnosis.
2. Once they tell you what is wrong, repair/replace the defective parts yourself.
3. Once you have replaced the defective parts, take the vehicle back to the same shop, tell them what you did, and have them evacuate and recharge the unit.

It might help if you do some research on auto AC systems, such as:

http://auto.howstuffworks.com/automo...nditioning.htm
sounds like my next step
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