Hey. 2001 f-350 7.3- AT,SB, DRW with 206000 miles. Aircon stops cooling when I stop at a light or get in town traffic. Works fine on the highway. But.... when on the highway with a trailer in tow, especially when hot out, the engine fan surges off and on for 1-2 minute periods and as soon as I turn the AC off, the surging stops. I mention this to see if it is a related factor. Any help would be appreciated. I will respond with updates as I progress. Thanks.

 

Check the video below, it is free and quick. May not be the problem, but worth a shot.

 

Thanks, I will give this a look see this week end. I'll let you know what I find.

 

One more thing to consider-the AC condenser coil sits in front of the radiator, so when it is hot out, the condenser is dumping a lot of hot air in front of the radiator, which eventually makes it's way to the fan clutch. I think your fan clutch is getting weak. If removing shims doesn't work, replace the fan clutch.

When the air flow through that condenser slows down, the freon pressure goes up, which can trip out the high pressure switch. This interrupts power to the AC compressor clutch, stopping the rotation of the compressor.

This is why in vehicles with electric clutches or electric fans, if the AC or defrost is turned on, the fan is activated. You don't have that option.
Larry

 

Does the AC actually quit, or just get less cool? Cuz that's normal at idle. Fan surging on and off is also normal when towing heavy in high heat.

There is a mod to the HVAC vacuum system that will increase the cooling on AC, check it out.

If you are idling for extended times and need AC, a tuner with a high idle setting is the ticket. Once I hit a traffic jam coming out of Las Vegas, idling while inching down a hill for about an hour. Pop up the high idle tune and all was cool in the desert for us.

 

I need to figure something out because last summer coming down the 395, coolant at 230*, EOT probably 240*, and bam..no more AC, til things settled down. Got me a new clutch kit since I'm outta shims and wanting to learn the cleaning out evap coil idea

 

Mine will basically stop cooling at idle. I'm assuming yours is doing the same. Try leaving it in park and bringing the rpms up and see if it works. I'm assuming mine is bad compressor as I even tried running a garden hose on the condenser thinking fan clutch and it still didn't work at idle.

 

Same symptoms I had several years back. I did two things, and both helped a lot. The temperatures from the vent in the cab dropped from warm down to about 40-41°F. At this point, now about 7 years and over 100,000 miles later, I still see vent temperatures in the 42-44°F range most of the year.

1) Remove a shim to re-establish the proper clutch air gap.

2) Insert a Ford Ranger heater valve in the line to the heater core.

The attached PDF files review each of these modifications in detail.

 

AC condensers also clogged up with road grime giving uneven cooling propertys. I've changed a couple at work due to road debris damage and boy that throw the AC so cold you can actually see vapor when you speak in front of a vent at idle.

 

Hey,
Sorry I haven't posted any results but I had the truck in a "Z" status for the last few weeks with glow plug valve cover R & R as well as induction boots and top end clean up. found one of the valve cover gaskets cracked in two places. Anyway, I pulled the AC inner compressor clutch wheel and found one spacer installed. I didn't feel comfortable running it with "NO" spacer so I installed a washer about half the thickness and threw it back together. Now the unit stays engaged when I am stopped in traffic and works as advertised. I also installed the heater hose recirculation valve mod (using the Ranger valve) and that's money! I also cleaned out all the crap stuck in the radiator fins as best I could as well. I'm putting it all to the test in a few weeks on a trip up to Michigan and back over a week or two. I'll post results when I get back. Thanks again for all the input and recommendations. I really appreciate the help. Hope to help out in any way if I can! holler at you soon. Spence

 

Thanks for the update and feedback! Excellent!! You're going to think you have a new A/C unit with those changes!

 

I only had one washer in mine two a couple of years ago. Removed it and it worked great. But now it some times dose the same thing. I'll be installing the new clutch soon and heater mod.