Thought this shuttle A/C was working fine, but then I left the truck idling while I grabbed some lunch, and when I came out it was blowing warm. Once I started driving, it cooled back down. Yet, when I first start it and leave it idling, it gets cold. Not sure if the engine warming up makes it go warm at idle, or if it's just the idling at whatever temps. What's typically wrong when the A/C gets warm idling?

 

High side pressure to high, insufficient air flow across condenser. Check the fan clutch and check the refrigerant pressure while idling.

 

 

Thanks guys. I checked the freon with the cheapo gauge that comes with a can of freon. It registered in the middle of the green area, but with the little dial set to the outside temp of 90, that's still low. So, I need to pay someone to such the air out, then refill with freon?

My truck was not getting cold either and I just added a can to it about a year ago and it got colder, then warmed up a little so I added another can a few months later. It never did get to where the cheapo gauge said it needed to be, but it's still cold. However, the fan doesn't blow strong on it, so it struggles to stay cool in the cab. I pulled the fan out and tried to clean that small condenser in there, but didn't get a lot better. I guess I need to pull the entire housing off and really clean it.

None of my trucks have every had great A/C, although my son's '06 blows strong and cold. My Eseries have all seemed to have duct issues or something - they blow warm air out the dash or under the dash, and a little cool air out the defrost vents. My Fseries have all had weak fan output, like that condenser is clogged up. I was able to clean that condenser in one of them and it started blowing strong. It's hot here in Texas; gets old driving in a lukecool truck.

 

I hear the fan kicking on a lot - that's a good thing, right? These Eseries get hotter in that tiny engine compartment.

 

No not really.
This is one of the things I won't do myself do to lack of a true manifold gauge set.

The ones on the store cans ain't worth the plastic and scrap metal there are made from.

You need to recover what is left in the system and then pull a vacuum and see if it holds.
Once you know that there are not any leaks then you can recharge to the specified amount
of the proper referent.

 

It's a complete waste of time using the cheap gauges found at Autozone, Advance Auto, etc. Hook up a good set, then remember high side readings will rise with ambient temp as well. Here's some general diagnostic rules for openers:

Low Pressure Low, High Pressure Low ----- low refrigerant charge

Low Side Normal, High Side Low ---- high side restriction

Low Side Normal /High, High Side Normal/High ---- system overcharged

Low Side High, High Side High ---- moisture in system

Low Side Low, High Side Normal --- faulty cycling switch

Low Side High, High Side high ---- inoperative cooling fan, blocked condensor

 

If you over charge it you'll slug the compressor. Not cheap. If you don't have the proper equipment and training it's cheaper in the long run to pay a pro.

 

Thanks for the advice, guys, and especially that summary 1990. That is very useful info.

Most of these auction trucks I buy have been sitting for several months and almost always have weak A/C. I just assumed that they lose freon over time and need a little up kick. It's worked a couple of times and didn't work a few others.

 

 

 

We replaced our with a Trane. So far so good.