First time using the a/c on my 97' F150 this year, having major problems with it now.

1. BIGGEST problem happened yesterday. I drove for about an hour with a/c blasting - look down and see my temp gauge bordering red. i turn off a/c and temp drops a little, but still pushing red.

Today, I drove for an hour without a/c and temp remained normal the whole time.

2. When i turn on a/c (norm or max) it causes engine to run very sluggish. Turn it off, and all is fine.

3. Engine makes a bit of a high-pitched 'chirping' sound when a/c is on.

4. While running a/c it randomly stops blowing for 10 seconds, then starts blowing again.


No water leaks and collant level is norm. Any help would be greatly appreciated, and I promise to post final solution if any are found!


Russ
-1997 F150, 2WD, 4.2 V6, 160,000 Miles. All original parts.

 

Sounds like you have airflow problems across the radiator and A/C condensor. You didn't say whether your problem was on the highway or in 'stop & go' traffic. If you are on the highway with the same symptom then its for sure an airflow and/or dirty radiator/condensor. This can be checked using a garden hose and misting the radiator and condensor. If the temp plummets then clean that dirty bastard and remove any grass and road debris.

Since you have a bit of mileage on the old gal, there may be a good chance that both the radiator and the condensor may have some clogged pass-throughs.

 

It's also highly probable that, if the fan clutch is original, that it's probably reached the end of its road.

For item # 4, clarify it the blower fan's operation is interrupted, if the airflow is intermittently defaulting to defrost, or if the blower and airflow are constant but it is the cooling capability that is varying.

A restriction of the condensor/radiator's airflow or a weak fan clutch causes the compressor to have to work extra hard to operate. This would explain most of your symtoms (the chirping is probably from a bearing, perhaps overstressed).

Steve

 

Bugman, it happened in both driving conditions. I first noticed the high temp on the highway, but once I turned off the a/c I was still pushing redline for 10 minutes in stop and go traffic. However, this only happened after running my a/c for over an hour.

Yesterday and today, my temp has remained normal while not running my a/c on hour long trips.

Are you saying that the airflow issue is related to outside grime or inside the air tubing? My engine/radiator/compressor dont look very dirty.

I'll try all your suggestions and get back asap!

Thanks for the quick reply!

Russ

 

I'm not really sure why I did not suggest the same as Steve; the fan clutch is always questionable and is usually the first thing I replace. They are also hard to tell if they are working properly.

You may have several problems that add up to over-heating. At the very least do the following:

1.) Replace fan clutch (they're not too expensive).
2.) Use some type of cleaner to clean both the radiator & condensor.
3.) Do a radiator flush & refill.

Report back your findings.