A/C cuting out, catalitic conv.

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

5 Replies

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

RAMMER

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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

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

RAMMER

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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

DPWD23

MECHANIC
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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!