Automotive Air Conditioning Information Forum (Archives)

Provided by

We've updated our forums!
Click here to visit the new forum

Archive Home

Search Auto AC Forum Archives

Newbie Question on Frost

AMDPower on Fri August 06, 2010 6:41 AM User is offline

Year: 2002
Make: Jeep
Model: Wrangler
Engine Size: 2.5L
Refrigerant Type: R134A
Country of Origin: United States

Hi guys. I'm new here and it looks like there is a wealth of information. So, here it goes.

I installed an aftermarket AMA complete kit in my 2002 Jeep Wrangler 4 Cyl. that never had air. Installation went smooth and had it charged the next day. A/C seemed to work great. About a week later (yesterday), I came to work early. It was only about 68 degrees and moderately humid. I had the A/C on full blast mostly because I've had so much fun driving with A/C after 8 years of none! It was chilly inside until about half way to work when it started blowing warm air. When I got to work (total trip about 4 miles), I found that the low side? of the evaporator (the one with the expansion valve) was frozen with a lot of frost between the valve and the firewall. I called AMA who was very helpful and suggested that I was probably low on charge. I started thinking later in the day and realized that I installed the expansion valve probe on the wrong side of the evaporator! I called them back and they said yes, that could cause the freeze up. I fixed it at work and drove home. So, today I came into work with nearly the exact same conditions. I had the A/C on max with the fan on Mid/Low. It was nice and chilly the entire way to work. I popped the hood just to check and found a little bit of frost in the same spot. I touched it and watched and it thawed very quickly (maybe 30-40 seconds).

So, my question is this... Everything seems to be working fine now(though it was a short trip). There's no frost (just condensation) in that spot under hot or non-humid conditions. The little frost was only in the morning. Is a little bit of frost normal in that position or is it still possible that I have too little charge? The mechanic that charged it for me said he put in 24oz. just like I asked and check for leaks on the machine before he charged. He charged from a tank and not cans.

Am I good to go or should I be worried that's undercharged or has a leak?


Edited: Fri August 06, 2010 at 6:46 AM by AMDPower

dasinc on Mon August 09, 2010 7:04 PM User is offlineView users profile

Sounds to me like the evaporator is freezing up. I'm not familiar with the AMA kit. What are they using for a thermostat to measure evapoator temperature. If it's a bi-metal thermostat it's possible that it is inserted too far into the evaporator so that the sensing tip is actually pushed our the other side, or possibly a defective thermostat. To test you can run the a/c, recirculate the air, have all the windows closed and measure the vent temperature with the blower on low. it should get cold enough to cycle out the compressor. It should not go below 37-38 degrees before cycling the compressor out.

Take care,


TRB on Mon August 09, 2010 9:52 PM User is offlineView users profile

Preset thermostat. Customer inserts probe during installing. Is the valve wrapped with the tar tape that was sent with the kit?


When considering your next auto A/C purchase, please consider the site that supports you:

AMDPower on Fri August 20, 2010 1:16 PM User is offline

Yes. Tar tape applied. Actually, I think all is good. Just get that little bit of frost early in the morning if humid. It's really been running great. Hasn't frozen up since I changed the sensor position to the right side of the evaporator. I also had the wrong vacuum switch sent for my dash that AMA was quick to correct. No more problems that i can see.

Back to Automotive Air Conditioning Forum

We've updated our forums!
Click here to visit the new forum

Archive Home

Copyright © 2016 Arizona Mobile Air Inc.