Hey all, I have a 94 F150 with a 302 and an auto. My problem is this.... When I first start the truck for the day regardless of outside temp the air works great. How ever when I turn off the truck even for as little as 5 minutes, it blows out warm muggy air even if I rev the engine. It then takes 3-5 minutes of driving for the air to cool back off. Some one please help!!! The air blows ice cold when it gets going.

Also When I accellerate hard like going up hill or merging, the air will stop blowing out of the vents and come out the feet and defrost. Thank you in advance...


Bill

 

You have a vacuum leak somewhere in the AC duct system. When you shut it off the vacuum bleeds off and you are sucking in fresh air untill the vacuum catches up to suck the recirc door back open,if it ever opens...quite possibly you are simply cooling outside air all the time. I would look at the white vacuum tube on the passenger side of the engine compartment first. They are notorious for cracking up and falling apart. It attaches to the fresh air door actuator near the cowl area and the evaporator box.

 

Thank you so much!! I found that the white hose going in to the recirc door had a small crack in it. I cut the end and replaced the boot and it works like never before. Again thank you so much.

Bill

 

Great, glad to help..

 

Thanks Homer you the man. I was having the same problem with my 91'. I thought it just had somthing to do with my changing over to R-134 (which actually went well) I just read this post and went outside and checked and sure enough the little white vacuum hose was cracked. I was just cooling outside air this explains why it cooled great in the mornings and took forever to cool down on a hot Oklahoma afternoon.......THANKS

 

Great Stampede, glad that took care of it for you. Ive seen this many times in the past 7 years and am just passing on what Ive learned.

We Okies have to find a way to keep cool or we would roast in this hot sun where it seldom rains ..

 

I have read the responses hear hope you can help me. I have a compressor that is knocking. It is rebuilt and just installed. In fact the whole system is new. I made the mistake of listening to a contact that told me I did not have to vacuum the system prior to installing R134a so I just filled it up and ran it for a while. Now the compressor is knocking. I had the system evacuated yesterday and charged it last night but an having the same results. Any thoughts?

Scott

 

srm235 Did you pre-oil the compressor when you installed it? Any time the sytem is opened, it must be vacuumed before recharging.

 

yes I did pre oil the compressor. After installing the compressor I converted the system to 134a and had the system evac and charged and discovered the condensor was leaking. I then replaced the condensor and recharged it without vacuum. I realize that was a problem now but it is now vaccumed.

Do i need to re-oil? If so how do you do that? Do i have to take the compressor off to do that? Could this damage the compressor if I continue to run it making that noise?

Thanks for your thoughts.

 

I have another question here. After the installation of the compressor I had the entire system flushed. does that remove the pre-oil?

 

When you pre-oil the compressor with about 4 ounces of oil, and reinstall it, it should be rotated by hand several revolutions each way to expell any excess oil into the system so it doesn't get oil locked when you start it up.

ON EDIT:
If you flushed the whole system again, with the exception of the compressor, yes you need to refill the system oil, less the oil in the compressor, which should be about 2 ounces, I believe.

 

i put 4 oz of oil in the system then had it evacuated and then put 4 more in the system. Could i have to much oil. It almost sounds like a bearing making noise. is that possible? is it possible the system is vapor locked? any other thoughts?

You help is appreciated.

 

Based on all you have explained, your compressor has somehow been damaged. Who knows how the system was flushed and if all the solvent was removed. If any solvent remained and you didn't evacuate the system, then the solvent could have gotten to the compressor and friction ate something. If you ran with low oil, friction. If you just replaced the compressor, yank it out and get another one and maybe they will exchange it, ask first. IF they don't exchange it, just run it til it quits then replace it.

It's not vapor locked. Nothing you can do here except wait or replace now.

 

If you ran it any length of time after you recharged it, without evacuating the system before the recharge, you can be sure that knocking in your compressor will be fatal for it.

If you don't evacuate the system, you leave moisture in the system. This moisture is not condensable at the same pressure as the refrigerant is. The result is super high pressures that your system is not designed for. This is probably what caused the leak in your condenser coil and unfortunately the eventual demise of your compressor.

 

I have a 94' Econoline Van. When the a/c is turned off, moist warm air still comes in the BACK vents. There is no separate motor for back a/c. Where would I check for cracks in hose on the back venting (runs along the driver's side to the back sides).
TomMc