My Dad's AC is acting up very annoying.

[Brett F.]

Hey guys I have looked all over the place and know I should have come here first but... My dad is 65 and his truck gmc sierra is acting very strange. Yeah not really Ford but need help with this.

I searched and didn't really find any help either so here goes.

My dad took his truck to a shade tree ac guy and the guy went to check his ac by shorting the low pressure switch to get the compressor to kick on. The problem is the idiot didn't know what he was doing and shorted something different out. What, I don't know. he then got the right one and charged it and it works fine, well almost.

Now what happens when he first turns it on is a thumping sound like something is opening and closing for about 30 seconds and then it stops. Then when he turns off the truck it does it agian. It may do it while driving once in a while and sometimes it doesn't do it at all.

Any ideas? I know it seems vague but it's the most info I have on it.

If you could help me out I would appreciate it.

 

[Brock94]

Where's the thumping sound coming from? Is it one thump or several at a time? If it's in the passenger compartment, it could be a blend door or a mode door in the HVAC unit.

 

[gensic11]

if the mechanic ***ed it up - tell him to fix it

 

[Brett F.]

It is several times and it does sound like a door or something. I think, without really knowing, is that it is a solenoid that opens and closes the blend door and it is just opening and closing the door about 15 or so times at a time.

The shade tree mechanic has since fired the guy and gave dad a run around so I have decided to see if I can get it fixed for him. He is on a fixed income and I don't have a lot of extra $$ right now.

Thanks for any help.