I'm brand new here folks and hope someone can help me out. I just bought the truck referenced above. Nice truck. 71,000 original miles. It had a check engine light on when I got it. I replaced the O2 sensor and the EGR valve and the light is now gone. I do have a couple of other problems that have me scratching my head. The A/C is not getting cold. I tried recharging the system. I replaced the low pressure switch because the compressor wasn't cycling. Now, the low pressure side lnes and accumulator are cool enough to have condensation. But the high pressure lines are hot and the air still isn't getting cold. Any ideas?

 

The high pressure lines are supposed to get hot.

 

That clears that up glc. Thanks. Any idea why the air's not getting cold even though the compressor is cycling and the low side pressure is cycling between 30 and 50 psi?

 

I don't know the particular system, but I'd suspect something isn't right with whatever it uses to control the temperature of the air - blend door system or something. The air isn't going through the evaporator or it's getting reheated or something. Possibly a vacuum issue, if this is a vacuum controlled system - or a cable if it's cable controlled.

 

Does the fan come on? Some years ago I had the same issue and wound up replacing the fan switch. It can also be somewhat of a hassle to get the temperature slider coupled to the cable just right.

 

The radiator fan works fine and the A/C blower works fine. The vents have a strong air flow out of them. I noticed that the coupling right behind the low pressure valve got cold enough to form frost when I was adding the 134A. The compressor cycles about every 15 seconds. I ordered a vacuum so I can evac the system and start over. I didn't do that the first time. I just added 134A. I'll let you know what happens. If anyone has any better ideas, I'm all ears! I appreciate the info.

 

If it is cycling on and off, it is probably low. If you overcharge the system, it won't cool either. Make sure the fan clutch is good. It should spin with some resistance by hand. If you cut the truck off and the fan is still spinning freely, the clutch is bad. Does it cool as you drive down the road? 92 was still R12 when built. Someone has converted it. If you evacuate the entire system and refill, refill it with only 80% of the intended R12 charge. There will be a label by the radiator which will tell you how much freon it holds and the type it had when built. Before you refill it, remove the orifice tube and replace it with an orange one (they are color coded for the orifice size). The orifice tube is located in the bottom line of the evaporator. You can follow the small hose from the pass. side of the radiator to the plastic box that houses the evaporator. Remove this line (special tool required) and the orifice will be inside. Also takes a special tool to remove that.

 

Thanks for the info bigbronc. The fan seems to be working fine. It does not spin when the truck is turned off. I'll try evacing the system, changing the orifice tube and I'll give the condensor a good cleaning. If there's moisture collected in the bottom of the evaporator should I take it off and dry it out or will vaccuming the system take care of that? Thanks again for all of the good info.

 

Vacuum pump will remove moisture. Let it run for an hour or so before charging.

 

Make sure you close the valves on the gauge set before turning the vacuum pump off, or you will just suck moist air back into the system.

 

Thanks for the tips bigbronc and glc. I'll pick this back up when the vacuum I ordered comes in. I'll let you know how it goes.

 

OK. Received the vacuum pump. Pulled a vacuum for over an hour. Attempted to recharge system. If I get the low pressure side within the proper range (28-38 psi) the high side is too low (140 psi). I changed the orifice tube before pulling vacuum. It was really caked with the gray matter (not the good gray matter). Any ideas guys? I don't know where else to turn.

 

The gray stuff was the residue of some necessary parts of the compressor. That's why it can't make pressure any more. And that stuff is even thicker in the condenser, which can't be effectively cleaned - it has to be replaced, or that same gook will work its way back through to the new compressor, and you'll be doing this all over.

That's why it's best to just pay a pro for all refrigerant work. It'll cost you less in the long run, and take a lot less time.