a/c

joeman2199 · March 15, 2004

ok, in my 2000 tahoe, its had a history of needing to go back to the dealer to get the a/c checked and every other year b/c its just not cold enough for florida,the problem was always that it needed to be recharged (of coarse they never found a leak), the only problem is that im out of warranty now and i dont feel like payin $150 to have it looked at. my question is , would a low side pressure guage from the store be adequate to tell me if i have a low charge or do i need the high and low guage, b/c some of the kits at the store only come with the low side.

citydriver · March 15, 2004

A/C can be tricky A low side gauge will workif you know what ur lookin @

Operating pressures will vary depending on outside (ambient) air temp..You wanna make sure that you dont overcharge the system,that will only do more damage It may be worth havin it checked again at a GOOD shop..the hard part is finding 1 I'm sure you dont wanna hear that

I 4got to add this: If its been in the shop so many times 4 the same warranty repairs,theres a record of it..Try callin a GM rep IT may be worth the effort

Shaners · March 15, 2004

I was told by a GM Tech Guy once that these A/C units with the new refrigerant are very sensitive, and that even 1/2 lb low can make their cooling capabillities less than adaquate.

SteveCZ · March 15, 2004

Kind of like the coolant reservoir being a half an inch below the "cold full" line gives you air pockets in your heater core

joeman2199 · March 15, 2004

bought the test kit, its 78 outside, and the truck gets down to 50. my 2002 got down to 36. the test gauge showed about 45 psi on the low side. where should i go from here, is that low for the GM or what.

wisconsinz71 · March 15, 2004

45 sounds kind of high for only 78 ambient degrees. With the ccot system something you could try is feel the accumulator and feel the inlet to the evaporator. The accumulator should be as cold or colder than the inlet. If your overcharged you wont get good evaporation in the evaporator and it wont be efficient. If undercharged the system wont have enough refrigerant to work with to soak up heat. Unfortunately the only real way to know where your at it reclaim it and recharge with the right amount.

joeman2199 · March 15, 2004

what is a fair price to have a pro look at this?

citydriver · March 16, 2004

Up here in western NY the goin rate is about $45-50...includes up to a pound of R134a...last time I looked...45psi sounds kinda high to me also for 78F...my '95 sucks down to 25-30 psi in that temp LAST SUMMER UP HERE (we be lookin at 4-6" snow for 2mrw ) Any how,make sure the service includes a LEAK CHECK,Aso let the tech know about the systems past history so they look harder just my .02

joeman2199 · March 16, 2004

well, i had a panic last night as i was informed by an expert that if you use the recharge stuff, (unfourtunately i used half), which uses the leak sealer and the ester oil, that it can really mess up your system and contaminate it. so the person told me that i may need to have the entire system flushed and redone, and that would run $500 mininmun. so i took it today to my local a/c shop and showed them the stuff i used, and they told my that it wasnt really a big deal and, somehow it was working fine, pressure was right and it was blowing at 40 degress. what a relief. so hopefully this thing will work thru the summer (november for FL) and things will be alrite.

a word to the wise for anyone dealing with the A/C, DON"T use anything with the leak sealer in it. read that article. next time i will definitelly be more carefull about what goes into my a/c system

http://www.motor.com/MAGAZINE/Pdf/042003_04.pdf

citydriver · March 19, 2004

COOL But yhe next time someone gives you an estimate for $500 for ANYTHING w/o lookin @ it,get another opinion

OUMike · March 21, 2004

Ambient temperature has less to do with pressures than one might think. Unless of course you are on one extreme or the other. I live in Houston, TX and just had to deal with AC trouble and pressure were not effected by ambient temperatures. You will need both the low and high side to determine what the problem is. Only this way will you be able to determine if your compressor is bad or not. I say replace it yourself. Better AC and worth the money. Compressors for OBS are about $250..I can't emagine a NBS bein' any more expensive.

I was told by a GM Tech Guy once that these A/C units with the new refrigerant are very sensitive, and that even 1/2 lb low can make their cooling capabillities less than adaquate.

This is very true. Even the slightest drop in pressure CAN cause the unit to not perform as well as it should. However it is possible that my 94' could have had a leak for a solid year before it became a problem. So I don't think this is true in all cases.

Good Luck