A/C cuting out, catalitic conv.

Tiny
RAMMER
  • MEMBER
  • DODGE RAM
96 ram 5.2, 148k mi, 2wd, Under light load the AC cuts out. No codes. Thinking map sens. But checked ok, tps checked ok. A/C blows cold air with no load. Thinking has something to do with a wideopen throttle switch bad or something similar. Also have a rattle coming from exhaust. Fwd area. Tail pipe is extremely hot. Could all this be caused by a bad cat. Conv. Truck seems to be lacking alittle power but it is tired. :D
Thursday, July 12th, 2007 AT 8:45 PM

5 Replies

Tiny
DPWD23
  • MECHANIC
  • 136 POSTS
Use a gauge to check the charge of the a/c system. If the low side seems too high, you could have a problem with the orfice tube or the valves in the compressor.
If you open the throttle a little, does the compressor clutch disengage? Or does it just not blow as cold of air when you are accelerating?
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Thursday, July 19th, 2007 AT 11:48 PM
Tiny
RAMMER
  • MEMBER
  • 5 POSTS
Yes the clutch disengages and the fan quits blowing. When acceleration eases it all comes back on and can hear the air doors move.
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Friday, July 20th, 2007 AT 6:58 PM
Tiny
DPWD23
  • MECHANIC
  • 136 POSTS
I'll need more time to investegate this one. If the air doors are moving, and the compressor is turning off, and the fan quits on acceleration, it's a MUCH more in depth problem than just a charge. I'll try to find some wire diagrams and see what runs where.
It is a possibility that something is getting shorted out. Just don't know what yet. If I can't fin out the solution, maybe we can work to eliminate some possabilities before turning it over to someone else.
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Saturday, July 21st, 2007 AT 12:01 AM
Tiny
RAMMER
  • MEMBER
  • 5 POSTS
I'll need more time to investegate this one. If the air doors are moving, and the compressor is turning off, and the fan quits on acceleration, it's a MUCH more in depth problem than just a charge. I'll try to find some wire diagrams and see what runs where.
It is a possibility that something is getting shorted out. Just don't know what yet. If I can't fin out the solution, maybe we can work to eliminate some possabilities before turning it over to someone else.[/Quote:4fdb18a1b3]At 1st I thought it was vacuum related. I was thinking map sensor. It seems like the wide open throttle switch was kicking in early. I thought that was controlled by the map sensor. The truck runs fine other than the rattle coming from the catalytic converter. Are the a/c controls run by vacuum? That was another thought I had. It deffently has something to do with engine load. Thanks for all of your help.
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Sunday, July 22nd, 2007 AT 2:41 PM
Tiny
DPWD23
  • MECHANIC
  • 136 POSTS
My brother has a similar truck. I will check out the A/C controls tomorrow or Tuesday and get back to you. I have a pre-op appointment on Wednesday and Sholder surgery on Thursday so after that it may be a little while before I can get back with you. I will give him a call and ask him to take his repair manual with him to work, and drop it by my house on his way home.
With a little diligance we will get this one figured out!
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Sunday, July 22nd, 2007 AT 9:02 PM

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