Isuzu Trooper A/C Problem

jjoker

Please Help!! I have a 1995 Isuzu trooper and the AC dosen't work at all. I have tried a lot of different things and paid a shop $600.00 to fix it but it still dose not work. Here is what I have done.

1.) Replaced the Condenser
2.) Replaced the receiver/drier
3.) Vacuumed out lines
4.) refilled with coolant and leak sealer w/ oil

My system has a slow leak somewhere(A shop couldn't find it with a feeler gauge) but the leak is very small. I have a pressure gauge that I bought from Autozone and when I fill the lines with coolant the system says that it is at the proper pressure. The blower works but the air that is coming out is semi-cool at best. I was thinking the problem could be with the evaporator but that is a guess. The only other part I haven't messed with is the compressor but I would think if the gauge says its at the correct pressure it should be ok. Any ideas? Thanks!!

atfdmike

First off, a feeler gauge is NOT the way you find a leak. If you mean that the compressor is running, then you must have at least 35 lbs of pressure for the system to turn on. If it is on, then you should be able to monitor the pressure and see it increase and decrease on the suction side if the system is working correctly. If it is under or over filled, you will also have no cool air. The amount you add really has to be carefully installed. The sight glass at condenser should be clear or bubbling slightly in a proper system. You really need the particular refrigerant sensor to find a leak. Some dye compounds made for AC systems work, but only if it is in an exposed area. Refrigerant,as you are learning, can escape through miniscule openings. Most likely, and assuming your compressor is OK, then refrigerant is escaping. A system which cannot hold a vacuum after pumping it down is a sure sign that there is still a leak. At this point You need to determine if you have a leak. That means that if you put your gauge on at ambient temperature with the AC off, the refrigerant should have a pressure close to the temperature outside, or if it is R134 it may be a little different, but either way, should be there each time you check it. If you don't have pressure you don't have refrigerant. It is leaking out and air is getting in the system. If pressure is OK, and compressor is OK, and coolant charge is OK, then the expansion valve may be the culprit. They are touchy and a job to replace. I don't think they can be adjusted.
Anyway, You need to determine exactly what you have now after the work you have done. How much refrigerant did you install, was it the right refrigerant, Is there around 80# in the lines at rest? If there is, then system is holding pressure. If the compressor is running and you find no frosted lines at receiver\dryer or coming from the evaporator, then possible compressor seal problem. You need dual gauges to check compressor; when you turn off AC, if the pressure equalizes rapidly (withing a few seconds, then comp seal is bad and compressor is usually replaced). If with dual guages you have very high pressure on condenser side (300#+), then possible expansion valve problems. AC is a difficult area to diagnose. Eliminate the basic causes like low or no pressure, leaking o rings at joints, dirty condenser, bad dryer and then the big ticket items like compressor or expansion valve are all that are left, IMO!
Hope this helps.

bigtim1763

My A/C wont come on unless I move the circulate or non circulation (the thing that has a little pic of the cars air flow from the vents) bar right to left really fast. even then it doesnt blow very hard at all?

XonURhed

I have a 2001 trooper v6 with a low voltage problem.The compressor doesnt seem to be getting the correct amount of volts from the computer to activate.My mechanic says the solution to this is either a:new computer or b: bypassing the computer with an manual switch tied into the thermostat and a 12 volt directly to the compressor.Is this a good Idea.Or could it be my alternator.I have read were the after market alternators are sub-par and may not be giving the system the right volts.The mechanic has checked for shorts throughout the system and spent alot of time checking the wiring.Any thoughts would be greatly appreciated.I would rather fix this problem the right way.