The A/C on my 03 6.0 f-350 works intermittently at idle. I hooked up the gauges and what I found is the high pressure climbs to around 400 psi and then the compressor kicks out (hence the warm air) After the pressure comes down the compressor will kick on again and the temp coming out of the vents inside (ac on max) will cool back down to about 58. (Ambient air temp 92 deg) This cycling continues while at idle, and seems to line out perfectly when driving on the road. I initially thought I might have a prob with blockage in the dryer or a line, however that doesn't make sense if the a/c works fine when moving.

I have read through various posts for the last 24 hours and the only thing I have run across is a possible fan clutch issue? On one occassion while testing, the fan clutch engaged while at idle and the a/c high pressure seemed to stay around 220, could the fan clutch be a prob? Is the clutch supposed to engage when the ac is set to max? What are possible signs of a worn clutch like exists on the 6.0 diesel?

 

The fan clutch is independant of the A/C. It should lock up when needed.

Take a good look at the A/C condenser coils. Make sure they aren't packed with crud, bugs, etc. The fact that everything works OK when moving points toward an airflow problem.

 

My vote is a cloged condenser coil causing the high head. What was you suction pressure?

 

Thanks for the info. My head pressure on the suction side didn't change much (stayed around 35-40 psi) until the compressor kicked out then it equalized with the high side.

I guess I better start looking at the condenser. Is there a reliable way to test the condenser coil?

 

your not getting enough air flow through the condensor. i am going with a fan clutch because if it was a condensor issue it would do it all the time. you may need to pressure wash the front of your truck if it looks like no airflow can get through it.

 

Bowtie is right! Thats why it works ok going down the road-lots of air going through the condenser. The fan should pull it through when sitting still (it doesn't). My vote--fan clutch.

 

It's not like I need to back-up two Ford tech's, but I will :-)
Be careful with the pressure wash... Those transmission/radiator/various-and-sundry cooling core fins fold over like mad under too much pressure (yes, I bent some of mine).

 

OK--relevent question. How do you check the fan clutch. I NEVER hear my fan come on and my truck gets hotter than I think it should be. I do NOT have anything but the factory gauge. Is there something I can check manually or a way to make it accuate manually? My condensor is clean and the fins were just straightened (I'm **** so I do it about every 6 months with a small screwdriver) and it hasn't been more than 7 months since it was all out and everything cleaned. I'll get a laser temp sensor and check it if need be.

 

We had an issue a while back where they would show hot, but not be. Changed the cluster for that one. Using WDS/IDS, we can see when the pcm commands the fan on. Dont know if you have a scanner to access that pid or not.

 

I do not, but I think I'm fixin to take a ride down I-95 and give BTH a visit to let him reflash my truck, so I'll get him to check it out. My indash gauge never moves past "normal" temp, that is, where it always runs. Even when she gets repeated runs down the 1/4 mile. I've heard it come on one time and it was 3 gallons low on coolant--oh these many moons ago. Will the PCM read an actual temperature??? If so maybe my old Predator has that in the datalogger. I know it reads contribution codes, rpms digitally, volts, etc. Lots of good stuff. I'll have to drag it out and plug it in to see.

 

Don't let them overcharge you for the re-flash you still have warranty left don't you?

 

I'm under 100K so it should be under engine warranty right???????? What does anything I've done have to do with a flash???????

 

Exactly! Don't let them push you around.

 

here we go!!

 

Hats off to BTH for taking care of my flash and checking the engine fan. Everything is working great. I'm actually impressed at the performance of the stock flash. No turbo lag, no surging just a little puff of smoke here and there. Max EGT's were 1100 and that was gettin on it. I hit the speed limiter at 1050* and EGT's were falling even holding it at 107mph. Trans. shifting is a tad soft for me, but I'm used to some pretty crisp shifts and it's still learning. I did have an 0404 EGR code when I got home but that is to be expected and of no concern. Max boost was 27 or so. 75mph cruise EGT's varied from 800-900 depending on ambient temp. and because of thunderstorms in the area. Actually fairly close to what my high HP tune runs. Usually the ultracompII runs about 700* @ 80mph and the factory tune has always run hotter, but still well within acceptable limits.

I did get to go for a ride in an '08 6.4L while I was there and man was that a nice truck. Sorry for the drool on the mat, but ........yall know how it is. Plenty of power, QUIET inside and out. 60mph was just nothing but a dream cloud. Ride quality was quite excellent also. Maybe I can get the old lady to trade Granny off for a 6.4??? I can dream can't I.