Tapping the Blower fan relay makes my blower motor work

[Urbanburban22]

So here's the deal. A while back my blower motor went out. Put in a new Delco part and all is well. Now come December and the controls Intermittently work ( low, m1, m2, Hi). Then, they stop working. New Delco resistor, and relay were installed. Blower motor will work when controls are switched to Hi, But only after you tap the blower motor relay. This was true before and after the resistor and relay were replaced. I misplaced the old resistor otherwise I'd toss that back on and re test. Anyone ever see or hear of something like this?

 

[PrairieDrifter]

I had a brand new relay that would run the blower motor on high for 1-10 minutes, never the same amount of time, didn't matter conditions. It would always end up just switching off at any time. But I could instantly switch speeds and go back to high and it would work right away. I had a whole new system too.

The brand new relay would lose contact after running awhile. Replaced relay. All fixed.

 

[Urbanburban22]

My fan only works on low. Unless I switch it to HI, then tap the relay under the hood.

 

[PrairieDrifter]

My fan only works on low. Unless I switch it to HI, then tap the relay under the hood.

It sounds like your relay is bad anyways for that reason. I never tried tapping mine, but changing the speed off hi then back to hi it would always come back on. You need to test some wires for voltage readings on all speeds. Id hate to say a bad resistor too, but I had bad relay out of the box, sounds like you may have too, why not a resistor as well lol?

 

[Urbanburban22]

It sounds like your relay is bad anyways for that reason. I never tried tapping mine, but changing the speed off hi then back to hi it would always come back on. You need to test some wires for voltage readings on all speeds. Id hate to say a bad resistor too, but I had bad relay out of the box, sounds like you may have too, why not a resistor as well lol?

Once off hi, if I switch it back to hi I have to tap the relay again to get it to work. I'm having my parts guys order me a new one on gm warranty. Might do the same with the resistor. I will check voltages from the switch when selecting m1, m2, and hi. Just haven't done that yet. Figured it was weird enough to mention and see if anyone else has experienced this.

 

[Urbanburban22]

Warrantied the relay for another OEM ACDelco GM#19288389 and I'm still in the same situation. Blower motor ONLY runs on LO, Unless I go under the hood and Tap the relay, Specifically with the switch set to HI (M1&M2 do NOT work). I have a resistor on order with NAPA, but that was recently replaced. verified grounds are good end to end (0.1-0.2 Ohms), blower motor works when you supply 12v at the relay connector bridging red (terminal2) and purple(terminal1) wires. With switch in HI, 12v is also recorded at terminals 5&4 (Blue and Orange). With Switch in Position M2 12v is recorded at terminals 2&5 (red ignition & blue). With switch in position M1, 12v is recorded is the SAME terminals as Position M2 (2&5). Definiatley not a relay issue, I dont think it's a resistor. For sure not a blower motor, or power supply issue. That leads me to believe its the switch in the HVAC controls. Can anyone verify that my MM reading seem consistant with that of a bad switch? Or??

 

[squaredeal91]

On big yellow. Non a/c truck. It has a bad connection at the fan switch. Sometimes I have to switch it down to off and up to on quickly so as to jolt it and wiggle the pigtail to make it come back on i removed dash bezel and can manipulate fan by wiggling the pigtail. Have you checked that end of it also?

 

[Urbanburban22]

On big yellow. Non a/c truck. It has a bad connection at the fan switch. Sometimes I have to switch it down to off and up to on quickly so as to jolt it and wiggle the pigtail to make it come back on i removed dash bezel and can manipulate fan by wiggling the pigtail. Have you checked that end of it also?

No such luck with a sick move like that. I've got some down time at the shop today and plan to switch radios again, so I'll have the bezel off. I'll test the switch end of things, just want to see the PN before I order a new one. I'll update things later today.

 

[Urbanburban22]

UPDATE: Removed Blower motor switch from the HVAC controls. Disassembled the switch (whatch out theres 4 springs and a small ball bearing) found the once "grease" dried up and caused there to be no connection between the contacts on the dial and switch body. Cleaned and reinstalled. LO,M1,M2, and HI all work now. Still got a new one from NAPA, but the OEM will now be a spare.

Thanks all who helped!