88 k5 hi speed blower
 

Hi speed works intermittenly on ac/heat...Put in new resistor, no help...Could it need a new relay???

Possibly I would test to see if it is bad first though.

i had a k5 that did the same thing, and it ended up being the blower motor itself. and this was after i changed the resistor 3 times and the relay twice..

hope this helps

Ck1500

I'm having the same problem replaced the motor and relays. But no change low and med work but no high. the relay that controls it does activate i have to trigger it manually and it'll work. could it be the controller?

Did you ever trace down the issue?
 

I have had that very issue with my 88-K5 since the day I bought it. I was told there is both a resistor, and a relay, but the only one I know about is the one mounted on the side of the air conditioning housing.

hi speed blower problem
 

I had this problem 2 winters ago...Removed the new replacement motor because problem persisted...Discovered that the grounding of the motor was only partially connecting enough for low speed operation...Cleaned off paint where ground contact was made...Corrected problem...Easy check as follows: Remove motor, leave elec. hooked up and touch motor to a/c aluminum receiver...If switch is on HI position on panel, motor should turn at high speed...A little factory paint goes a long way toward screwing up a good dc ground....

I had this problem when I got my '89, and it turned out to be corroded contacts on the heavy gauge purple 12v wire where it hooks to the blower motor. I replaced the factory connector with a large female spade connector and it's been fine since, except when I pulled that wire loose once...