Blower Motor ?

[RocketKing]

My blower motor would work only on medium. I checked the high speed relay and sure enough it was not grounded, after I grounded the relay high speed will work but when you switch from med to high the blower goes off and hesitates about 2 or 3 seconds before coming back on in high. I have never seen anything like that before any suggestions?

I still do not have low speed but I think that may be due to a bad resistor, would a bad resistor make the high speed relay hesitate, I can't imagine why it would but just throwing it out there.

Any help would be appreciated, thanks!

[bonnieclyde100]

i would say either your switch or relay is bad. as far as not working on low either your switch or your coil resister the is in the heater core box is bad. seeing as it wont work in low and hesitates to high i would check the switch first by bypassing the switch and send the power straight to the relay and see if it hesitates then.

[leddzepp]

bad relay

[RocketKing]

Thanks guys. I have already changed the switch out, so I will now change out the resistor and relay. Might as well consider changing the A/C compression switch while I am in there.

When I was crawling around in the floorboard I also realized my new diverter box is broke...one step forward and two back. lol

[mrein3]

Originally Posted by RocketKing

My blower motor would work only on medium. I checked the high speed relay and sure enough it was not grounded, after I grounded the relay high speed will work but when you switch from med to high the blower goes off and hesitates about 2 or 3 seconds before coming back on in high. I have never seen anything like that before any suggestions?

I still do not have low speed but I think that may be due to a bad resistor, would a bad resistor make the high speed relay hesitate, I can't imagine why it would but just throwing it out there.

Any help would be appreciated, thanks!

GM designed this system with, in my opinion, too small a gauge of wire. I guess that is a tad unfair, it probably works as designed with new wire. But add 40 years of heat cycles, cracked insulation, and corrosion on the connectors, you get problems.

I would look at ALL connectors and ALL wire. And be prepared to fix them all.

When I converted to AC, EVERY truck I found with wiring in the junk yard had the connector behind the switch melted. If any of those wires cross, you defeat the design which is probably what is happening here - with you only having high (sort of a separate circuit) and medium. A bad resistor would cause you to only have one speed other than high and do check that first but I'd be prepared to rehab the whole system.

I ended up with a new switch, a new connector behind it, and I believe new connector inserts on the other end by the resistor (it has been a while since I did this).

Get on the google and look up NAPA part number 725147. If it isn't that one it is 725145. Which ever one of those two part numbers is the female one you're going to need a dozen or so of them. You can get a new switch and plastic connector from any supplier.

[Katrina/10]

The low speed uses both resistors, the medium only one, and the high none. my blower would not work on low speed, I replaced the motor and it worked fine.