A.C. Problems

[f.p.]

I have a 99 Suburban C1500 5.7, Last year I ran my air conditioner during the first warm day of the year and it blew warm air. I had the system charged and now it blows cold in the back and warm in the front. The system will cool the interior but it takes a long time. I plan on getting it fixed before it gets hot. Any help is appreciated.

[brcidd]

A 99 burban probably has the infamous "belly leaker" if you still have the OEM compressor- you are probably losing cooling due to a loss of refrigerant due to a leak- especially if the belly of the HT-6 compresor is oily/greasy- the best thing to do to confirm this is to have the refrigerant extracted and weighed- compare this to the factory charge amount specified on the accumulator- if less than half the proper amount- this is why your cooling is amiss- these compressors can be rebuilt- but most just replace them....

[f.p.]

Ok thanks, is the possible leak also the reason for the rear air being cold and front air hot?

[j cAT]

Originally Posted by f.p.

Ok thanks, is the possible leak also the reason for the rear air being cold and front air hot?

this to me is the temperature control door its stuck,, or motor is defective...... on your a/c compressor if it losses its charge again,,, add more refrigerant oil, this will keep seal of compressor from losing charge...It is very common with my experience with GM vehicles that at the factory they do not add the proper amount of oil....my own vehicle was low on charge 1.5years old like you after winter I added a 6oz oil charge and refrigerent and 5years later all is still good.......

[f.p.]

Thank you to both suggetions I will have both checked. Is there a way I can check the temperature control door? And is there an easy way to get to it to fix it?

[MT-2500]

Auto ac/heater controls?
If so a body capable scanner will check the control system.
But first get a good R-134a charge in it,
Low R-134a will cause many control problems.
MT

[777stickman]

To check the front temp control door do this:

1. Get the engine to operating temp.
2. Leave the A/C off!!
3. Turn the front blower fan on to med or high.
4. Select the upper vents for air discharge.
5. Turn the heat control to full hot-should feel hot air out of the vents
6. Turn the heat control to full cold-should feel air temp change to outside air temp.

If you don't feel any temp change at all the temp control door is inop.

[j cAT]

Originally Posted by f.p.

Thank you to both suggetions I will have both checked. Is there a way I can check the temperature control door? And is there an easy way to get to it to fix it?

this door is motor controlled, it is above the passenger side of the transmission hump mounted on/in the heater airbox/plenum. you could just replace this temp door contol module or have a repair tech that does a/c work,, fix/replace this part....this is a common failure item....

[f.p.]

I checked the door and it worked when I changed the temperature from cold to hot. I plan on taking it next week to get fixed by someone who repairs A.C. units on the side. I hope the can fix it

[j cAT]

Originally Posted by f.p.

I checked the door and it worked when I changed the temperature from cold to hot. I plan on taking it next week to get fixed by someone who repairs A.C. units on the side. I hope the can fix it

if the door moves then it must change temperature at air vents...


does the temperature vary from 130deg f at hottest to the air temp outside coldest , or then what temp do you see on the coldest setting....



if evaporator/ac unit is working properly you should see a 25deg drop in temp from outside temp at air vents with fan on max..

[Figaros]

f.p.
I had the same problem, front not so cold & rear nice & cold. I added 3 cans of 134a from walmart and kazaam...fixed! Pressure was just low enough that it couldn't get cooling to the front.

[brcidd]

That was a good test- but I would not call it fixed- it will leak out again--

Heck, when I blow a low tire up- I don't call that fixed- I expect it to be flat in a week or two until I find and fix the leak......

[MT-2500]

Originally Posted by Figaros

f.p.
I had the same problem, front not so cold & rear nice & cold. I added 3 cans of 134a from walmart and kazaam...fixed! Pressure was just low enough that it couldn't get cooling to the front.

It may be Kazamm or Wal mart K boomb

Wal Mart DEATH KITS

You cannot properly and safely recharge an air condition system with them.

The one side stop and go gauge does not tell you what your system is doing or is over charged or undercharged.
A overcharged or malfunction air condition system can reach over 500 lbs of pressure.
Enough to blow up that can or system and freeze you at first and the burn you or blind you and if any propane /butane in there blow and light you up.

The stop leak crap and who knows what kind of oil in the kits there will stop your system for sure.
Just like pouring super glue in it.
And some kits even contain freon with a butane mixer.
Good for a big blast.

If you are going to do it do it right and safe.
Here is what you need to start with.
http://www.ackits.com/merchant.mvc?S...erantGaugeSets

In the older days you could just throw in a can and go.
But over the years just adding freon is getting harder to do.
Newer systems have to have the correct amount of freon down to the ounces.
Most will need pumped down and vacuumed down and the right and amount of oil and a set amount freon charge installed to get the air to cool right and the system to last.
If an air condition is low there is usually a leak that needs fixed and also a lose of lubricating oil from system.
Also air and moisture enters a low system
If you are going to try to do it get the proper type air condition gauge set with the low and high side gauges.
Hook up the gauges and get a reading with compressor running at idle and at 2000 rpm on the high and low side.
Post back pressure reading and we can help you.
MT

[j cAT]

Originally Posted by brcidd

That was a good test- but I would not call it fixed- it will leak out again--

Heck, when I blow a low tire up- I don't call that fixed- I expect it to be flat in a week or two until I find and fix the leak......

if you do some research you will quickly learn auto a/c compressors are not a sealed unit as your refrigerator. these compressors leak at the shaft seal. this is normal for a auto a/c to loose 6-12oz. of refrigerant per year esp. in colder climates this is because the compressor cannot run at temps below 45deg f approx. if it did the compressor would try to pump liquid and soon destroy itself.... compressors only pump gases this is why care must be taken not to overcharge unit....as a result the shaft seal lacks the oil to keep refrigerant from leaking there.....my 2000 needed/refrigerant, oil after 1.5years, its now 2008 all is still good.


addition of oil is required when this loss is excessive.... i have found all a/c compressors GM has used over the years lacked the correct oil amount...
sometimes if the oil is real low the compressor will get noisey...


i had an 83 a/c compressor 17years and it worked better than the 2000 thats because r12 is a better refrigerant and because the capacity was 3lbs... which is about 2x what today's vehicles have so it took maybe 2min and all was cold now it takes 10min to cool down....

[brcidd]

It was normal to leak at the shaft seal- maybe 20 years ago but not in today's competitive markets- No current OEM car manufacturer would ever accept that outdated philosophy- shaft seals have come a long way- the double and triple lips don't leak- I have spent years studying this.

All compressors enter the assembly plant with the entire system oil charge in the compressor- if there is an oil loss, it is due to a leak- plus to determine system oil amounts- the entire system must be flushed and the oil trapped and accumulated and measured. I have done numerous oil retention by component studies. Noisy compressors are almost always the result of loss of charge- which does not circulate the oil properly- whether the entire oil amount is in there or not....