A/C system issue, speed related

[carbd86gt]

Ok guys, I have a strange issue going on with the A/C on my truck. I did a search but didn't find anything that I could use to help me track down what the probable issue may be.

The A/C on the truck blows ice cold as soon as it's turned on, but then it blows warm when I go over 65 mph Anything below 65, it works perfect. Now, I sped up to 80, let it get warm, then just took my foot off the pedal to let it coast, and as soon as I did that, a moment later it was blowing cold again while still being over 65 mph. My little sisters boyfriend was a Ford diesel tech for a long time and has since opened his own performance shop, so I took it to him. He knew a common problem was the shim for the clutch sometimes would cause a warm issue, so he removed it but the problem has not been fixed. I haven't taken it back to him to have him further diagnose the problem, but I'm more than capable of doing any wrenching on my own vehicles. I was a tech for a few years but now work on a performance shop specializing in Mustangs, but I'm not too familiar with the diesels just yet. Any help is appreciated! Thank you.

 

[powerboatr]

low charge volume can cause what you describe.
the compressor is moving lots more freon at higher engine rpms and if the volume is not up it can cause heat/cool issues

get some guages and put em on to check the volume/pressures

thats the only way to know for sure

or the orifice valve filter could be getting clogged...

 

[BIG JOE]

low charge volume can cause what you describe.
the compressor is moving lots more freon at higher engine rpms and if the volume is not up it can cause heat/cool issues

get some guages and put em on to check the volume/pressures

thats the only way to know for sure

or the orifice valve filter could be getting clogged...

What pb sez, and after that.. just behind the compresser is the pressure switch connector.. with the A/C on, give that a wiggle, if you can control the A/C clutch by moving the connector.... shut off the A/C and clean the connector pins ( a cut-down fingernail file works good). Kindofa Gremlin on these things ?

 

[carbd86gt]

Thanks for the advice fellas, I'll get on it this weekend and post up the results when I can!

 

[JLDickmon]

Thanks for the advice fellas, I'll get on it this weekend and post up the results when I can!

Dude..
diesel engine doesn't have anything to do with it..
mobile AC is mobile AC...
it's a cycling clutch orifice tube system. period.

 

[wilson111]

make sure the system is not low on freon. If the problem is still there you will need to replace the compressor. as always when you replace the compressor you need to replace the orfice tube and the drier also. i pulled the shim out of mine and got another 15k miles out of it. i figure 160k miles is not bad on the original compressor!

 

[carbd86gt]

Dude..
diesel engine doesn't have anything to do with it..
mobile AC is mobile AC...
it's a cycling clutch orifice tube system. period.

I understand that, I forgot to delete that part of my post. What I was going to explain was I thought maybe the truck could have a bad TPS, but the truck not having an actual throttle body led to be not mention that. My thinking was the TPS was telling the ECU that I was at WOT therefore having it turn off the A/C compressor during the WOT operation. Past that, I know how it works