A/C and heater motor questions

[anjieandjohn]

I am a lucky person....not only do I own a relatively decent vehicle in my 85 K5 but Uncle Sam pays me top dollar to spend my day looking through the thousands of posts on this website about how to make my before mentioned ride even better!!! Anyway, the real question is...my blower motor only works at one speed...high. Also, when switching between positions (i.e. defrost, vent, etc.), the idle tends to stay high until I turn it off or switch it from say defrost to heat. What are some of the things that could cause this to happen. I am still learning how to fix stuff (I just had a wonderful time replacing front leaf springs...damn metal bushing inserts!!)on my ride so forgive my ignorance.

 

[pauly383]

Your switch could be bad , or a relay , of equipped . Their is only one wire actually entering the blower motor in the engine compartment , so if it works at all it would have to be a relay or switch problem .

The idle raises because when you turn a/c or def on , the compressor comes on and the idle compensator bumps the idle up so it doesn't stall .

 

[Boondocks]

My 72 K5 had a resistor pack mounted in the unit, so airflow would keep it cool. If those resistor coils are broken, then only high will work (no resistor).

I'm not sure if your year works the same.

 

[diesel4me]

yup--resistor!

All GM trucks have a resistor in the heater box for the speeds..if you only get high speed,its likely the resistor has failed,or its plug where the wires go in are all corroded..its under the hood next to the blower motor on 73-87 trucks--I think the 67-72 trucks have it under the dash behind the glove box,in the heater duct box..

 

[anjieandjohn]

Thanks

I am going to pull the heater motor and replace it anyway and will go ahead and replace the blower resistor pack as well. I dont mind spending a little to fix the problem....As far as the idle, I understand why the idle goes up but it doesnt seem like the compressor is kicking on...I have no cold air on AC. I am going to go ahead and replace the compressor as well. It gets kind of warm here in VA Beach and I dont want to be driving the wife's minivan all the time because of the AC. I am going to go over to the Hobby Shop and they can purge the system and do refrigerant collection for something like $7.00 i think. I will put the new compressor on and the have them purge it again prior to filling it up again. I am going to the coversion as well. Thanks again for the help Fellas!!!!