Ac acting weird

[steved454]

I have a 1987 Chevy K5 blazer. I just had the AC compressor replaced. had a blow out on the old one, first time I have had that happen. Anyway now that it is fixed I notice the Ac stays on all the time unless I switch it over to heat. the off position, Max, ac and vent it stays on. Heater works fine and the temp works. it does not blow hot air out of the vents when I have the temp moved to the cool side. Do not want to go and randomly put parts on. Any ideas? Also when I have the AC on it runs perfect until I put it in gear then I hear ( not sure how to describe it) a rumbly sound.
thanks for any help

 

[steved454]

by blow out I mean the lines that go in the back of the Compressor blew all the oil and dye out of the it. O ring or something gave way.

 

[chengny]

Anyway now that it is fixed I notice the Ac stays on all the time unless I switch it over to heat. the off position, Max, ac and vent it stays on.

When you say that "the AC stays on", do you mean that the compressor clutch pulls in or are you referring to the cabin blower?

Other than pulling the plug off the old compressor - and pushing it back onto the new one, replacing an AC compressor generally does not require any work on (or changes to) the HVAC system wiring.

The AC system would only be considered to be "on" when the compressor clutch is energized. At that point, the belt/pulley is driving the compressor. With the compressor spinning, refrigerant is being pumped through the system and cooling occurs.


Put the selector lever in the OFF position and observe whether the clutch is engaged (it should not be). Then, move the lever to either the AC or MAX AC positions (temp lever all the way to cold) and note whether the clutch is now engaged and turning the compressor (it should be).

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[steved454]

Sorry i did not word it right. The compressor comes on and cold air blows with the selector switch in the off position, max ac, ac and vent. the compressor shuts off in the heat postition only. I can the clutch is engaging when when it is in the off postion and the others. It was doing this before the compressor went out.

 

[steved454]

the clutch is engaging with the selector in every position but the heat position.

 

[chengny]

It would be safe to assume that your selector switch is bad. Part number is 16001570. Looks like this:

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They are not hard to come by - or expensive. Here is the first one I found (of many) on ebay - $13.95:

http://www.ebay.com/itm/HS316-CHEV-GMC-PONT-A-C-HEATER-BLOWER-SW-16001570-/390255460605

Or if you'd rather buy from a standard vendor - Rockauto sells an original OEM/ACDELCO part for $23:

https://www.rockauto.com/catalog/moreinfo.php?pk=85233&cc=1061491&jnid=645&jpid=0


Classic parts has it for $28:

http://www.classicparts.com/1983-91...witch-w_-A_C/productinfo/68-477/#.VTMqfNIUXmU

 

[steved454]

Thank you for your help jerry.

 

[steved454]

Had the part on my Chevy shelf, replaced it and everything works great.