: Need Help Troubleshooting A/C



tlarwa
04-10-06, 10:41 PM
It's just now getting warm enough in Chicago to use the A/C, and
mine isn't working. The blower works fine, the thermostat works
fine (i.e. it kicks on the blower when it needs to) and the
compressor appears to work (I can hear it kick on and the RPMs rise
when the A/C button is pushed on and off). But there is no cold
air...

I checked the fuses under the dash in under the hood, and made sure
the relay was properly engaged. As I said, the compressor appears
to be working, so I don't think that's the problem anyway. I'm
thinking it's a freon leak. Does this car (2001 non-Sport) use a
freon charge, and if so, can it be recharged? If not, how do you go
about checking the charge?

Any troubleshooting suggestions would be appreciated. I's like to
get the cause nailed down before I resort to the shop to find the
problem. Other than that, the car is running great and is a joy to
drive. Just made a 1000 mile round trip from Chicago to Northern
Michigan with no troubles, and averaged about 26-27 mpg cruising at
75-80 mph. The car has about 75,000 miles. But, it'll be a loooong
summer without A/C!

Thanks for any help!

zonie77
04-11-06, 12:41 AM
AC isn't that hard but you have to get a set of gauges ($60-100) to do any diagnosing.

Is the compressor actually engaging? Look at the hub and see if it is spinning along with the outer pulley.

Here's a site to get you started.

http://www.autoacrepairs.com/index.html

AllenPacla
04-11-06, 06:08 AM
Try charging the freon first. There are a set of freon fill with gauges available at most auto parts which is easy to use. Just read the instructions.

tlarwa
04-11-06, 09:32 AM
Where exactly is the compressor? I'm not sure what to look for to see if the hub or outer pulley is spinning. Specifics would be appreciated!

AllenPacla
04-11-06, 04:29 PM
If you can identify the pipes leading to the AC, just follow it and it would lead you to the compressor. If I am not mistaken, it's on the driver side of the engine. The pulleys could be spinning but not engaging and therefore not actually turning the compressor. Anyway, try charging the freon first and see if it will cool your AC.

Elo
04-12-06, 05:29 PM
Also, the compressor has a refridgerant low-pressure shut-off mechanism...

When you turn on the AC, you may hear the compressor kick on for a second, but it will immediately shut off again...

I would follow others' advise and get the necessary gauges and some R134A refills and try that...

-Elo

Boris
04-13-06, 10:15 PM
and stop calling the refrigerant "freon".

Your car uses R-134a which you can get at any auto parts store(without an EPA certificate which is strange), buy the set with a hose and gauge, plug the hose into the low(suction) side and recharge if needed.

craigmm
07-28-06, 10:52 AM
i bought and used the r-134a on my caddy to no avail. still no cold air. everything seems fine just no cold air. i guess my next stop will be the dealer. any suggestions?

91TexasSeville
07-28-06, 12:54 PM
i bought and used the r-134a on my caddy to no avail. still no cold air. everything seems fine just no cold air. i guess my next stop will be the dealer. any suggestions?


When you write, "everything seems fine" we still don't know all the facts. Installing a used compressor ~or~ adding R-134A refrigerant is not enough information.

General Information:

At the time of a compressor install and "assuming" the used compressor is good, the receiver dryer, and evaporator expansion office tube should also be renewed. An outside vacuum source must be applied to completely dry the system. The system must hold that vacuum for a minimum of fifteen minutes after the vacuum source is removed. These steps must be perfomed BEFORE the system is charged with refrigerant. This applies to any brand vehicle.

Moisture and or particulates in the refrigerant will cause the HVAC system to suffer a cooling failure. That is why it is critical to find a leak in the system if a recharge is necessary. If a leak is on the high pressure side (compressor to condenser) it is less likely to pull moisture but if the leak is on the low side (evaporator to compressor) you are facing a frozen system and imminent compressor failure. Conversely, a leak on the high side will eventually cause an extreme low side drop in pressure which should trigger the low pressure switch that disengages the compressor clutch. On some cars the low pressure switch sets a code and causes a telltale display "low refrigerant pressure" or "compressor off" condition when the controls are set to cool or defog.

If one follows all the correct procedure for installing a new/used compressor and still have no cooling, then the ambient temperature is below 40 degrees Fahrenheit or there is a component failure on the control side of the system.

Charging an HVAC system without checking the pressures is like a blind man filling a glass of water with his hands in his pockets.

Accurate quality A/C gages are just as essential as a vacuum source when refurbishing an automotive HVAC system.

Specific Information:

We need to know the low and high side pressure displayed on your A/C gages when the system is set to maximum cooling.