A/C problem

[raidermark]

Hello,
On my 98 Suburban, 5.7; A/C was blowing warm air. I went to recharge & the charge didn't work & still showing low extremely low pressure. I noticed that the A/C clutch is not engaging when A/C is turned on. I tested by running a lead wire from the battery to the clutch on the compressor & the clutch then did engage. Could I be having an electrical issue or does the A/C have to be fully pressurized to engage the compressor clutch. I used 3 cans of 134a recharge with stop leak & still blowing warm air.

 

[Zaedock]

Looks like you have a decent size leak. There is a low pressure cut off switch to stop the compressor from cycling (to avoid damage). At this point, you could probably find and fix the leak, but you'll have to go to a shop to check for leaks, evacuate the system, and recharge.

 

[den]

You may have to use a jumper wire on the cut off switch at the acumulator too engage the the compressor so it will take freon?If the 3 cans were going in i would think it would engage.Jump the switch and try one more can.You probaly have rear air also?

 

[Trav]

This maybe difficult to obtain a satisfactory result from a forum. You will probably need a pro with testing equipment and gauges.
A few different things could be going on with this system.

It may have a large leak as pointed out where the pressure switch never allows the clutch to engage, or…
It has an electrical issue in which case it may now be 3 cans over filled. In this case even if the electrical fault were found you would not want to engage the clutch as component damage could be a real possibility. You will need to get the system evacuated and refilled.

Electrical diagnosis includes checking for power at the clutch terminal if none present start with the fuse and any relays, then power in and out from the A/C pressure switch, control panel, grounds etc.
You activated the a/c clutch so you know that works, it would have been helpful if you noticed if the line got cold and/or pressure readings when it was connected to power before adding 3 cans of refrigerant and stop leak. Do not jump the clutch now as parts may be damaged if overfilled.

I would probably take the car to a A/C service center. This could get expensive real fast tinkering with it.

 

[jstutz]

How low was the charge when you tried to charge it. I believe and make sure you double check, that a suburban with dual ac (front and back) call for about 65 oz of R134 and 11 OZ of oil. This is of course for a new dry system. These compressors are known as belly leakers.

 

[den]

I have a 1994 Suburban,would over a 15 year period would it leak enough freon to be charged?

 

[Trav]

Hard to say.Being a totally closed system theoretically it should remain full for the life of the car.Normally this isn't the case,some are tighter than others.The only way to tell is with a set of gauges,if the pressures are correct for the ambient temperature and the temp at the vents is within range then its fine.
If it still blows cold air and cools the car down in a reasonably short time i wouldn't worry about it.

We have a 13 yr old ford here that has never been charged and blows ice cold.

 

[Chris142]

4 common leak points on these trucks are.

1. High side hose where the pipe goes into hose near the
Compressor .

2. Compressor body.

3. Behind the passengers front wheel, kinda below the passengers feet. The aluminum lines rub and get a hole rubbed in them.

4.High side charge port.I replace every one I work on because they always leak.

 

[bullwinkle]

My old '94 Suburban actually has a slow leak from the low side line-if you look for the refrigeration oil, you'll generally find the leak-but if a coil is leaking, you'll need to put dye into the system and use a black light to look for dye coming out with the condensate (the water that drips on the ground when you run the A/C). If you look on the radiator core support, there should be a sticker with the total charge of R134A in ounces, and you'll need a gauge set and a vacuum pump to evacuate the system. If the system has air in it (which is a non-condensable gas) it will greatly reduce the amount of cooling, and could even damage the compressor.

 

[mechtech2]

All automotive AC
systems leak.
From the compressor seal, the line seals, and right through the rubber lines by osmosis.
How much? A little to a lot, even if things are in good shape. One Ford test showed an average of 7 ounces, but that seems a bit high.
Jump the compressor to fill it. You need 45 lbs or so for the low switch to complete the circuit.
It may be well worthwhile to add sauce kinda frequently, rather than a huge ACrepair bill.

 

[raidermark]

Thank you all for some great advice. This gives me a better idea where to start. Thanks again.