rear AC blower question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

aggiedave98 · 04-18-2005, 09:38 PM

My rear AC on my '89 suburban only works on high. I figured it was the restistor.

I finally decided to hunt it down (to find out it was really easy to find, but w/ the manuals you can never figure out where stuff is) and tested it. The resistors are in tack. I checked it w/ my ohm meter. There are actually 2 in series for some reason.

I then tested the voltage at the plug for the resistor and when the rear blower is on low, I get 12 volts there.

So what the heck is wrong w/ my rear AC on low??? High works fine.

screwballl · 04-20-2005, 10:08 AM

maybe it is the switch itself???? just an idea

aggiedave98 · 04-20-2005, 10:09 AM

but if it were the switch, I wouldn't get 12 volts at the resistor plug. When it's on high or off, I don't get 12 volts there. that's what I can't figure out.

88Jimmy4x4 · 04-25-2005, 01:40 PM

my 1990 just started doing the same thing, lemme know when you get it figured out

aggiedave98 · 04-25-2005, 02:03 PM

can you check the same things I checked:

I finally decided to hunt it down (to find out it was really easy to find, but w/ the manuals you can never figure out where stuff is) and tested it. The resistors are in tack. I checked it w/ my ohm meter. There are actually 2 in series for some reason.

I then tested the voltage at the plug for the resistor and when the rear blower is on low, I get 12 volts there.

also just curious, but can you test the voltages at the different terminals of the resistor pack?

thanks.

88Jimmy4x4 · 04-27-2005, 08:35 AM

I would check them, however I dont have a manual for that and have no idea where those components are.

screwballl · 04-27-2005, 09:33 PM

another idea.. the blower motor?
also did you test with the unit's ground or ground to the body when testing?? when the fan is say on low is there voltage still getting to the blower itself? is there voltage and continuity immediately after the switch AND at the motor on all speeds?

aggiedave98 · 05-02-2005, 01:33 PM

hmmm.. well what I tested was just the voltage across the resistor pack itself... from one terminal to the other. I didn't take off the rear cover to get to the motor yet. But, since it works on high and the resistor seems to be working, I'm not sure... I guess I need to look at the full wiring diagram and put together what's going on...

88J, I'll try and get some pics of what I'm talking about... if you upen your hood on the passenger's side of the truck near the firewall, there is a housing there. On the right side of that housing (as you're facing the firewall) there is a wiring harness going into that black housing. There are 2 screws that take it off and you just slip the resistor pack out. Then you can test between the different terminals.

04-18-2005, 09:38 PM	#1
aggiedave98 Senior Member Join Date: Aug 2003 Location: Sugar Land, TX Posts: 1,007	rear AC blower question My rear AC on my '89 suburban only works on high. I figured it was the restistor. I finally decided to hunt it down (to find out it was really easy to find, but w/ the manuals you can never figure out where stuff is) and tested it. The resistors are in tack. I checked it w/ my ohm meter. There are actually 2 in series for some reason. I then tested the voltage at the plug for the resistor and when the rear blower is on low, I get 12 volts there. So what the heck is wrong w/ my rear AC on low??? High works fine.

04-20-2005, 10:08 AM	#2
screwballl Tonawanda 454 Join Date: Mar 2004 Location: Liquid Sunshine State Posts: 2,754	maybe it is the switch itself???? just an idea __________________ 91 Chevy Suburban Tonawanda 454 R2500 - SOLD!!! 04 Dodge Durango 5.7L Hemi 2WD, 24K miles (as of July 2011) In the past 30 years about 90% of Fords are still on the road, the other 10% made it home. -------------------

04-25-2005, 01:40 PM	#4
88Jimmy4x4 Registered User Join Date: Oct 2003 Location: houston, texas Posts: 1,974	my 1990 just started doing the same thing, lemme know when you get it figured out __________________ 2008 Silverado Z71 RCSB 1991 GMC Jimmy 4x4 1976 GMC Sierra C15 SWB

04-27-2005, 08:35 AM	#6
88Jimmy4x4 Registered User Join Date: Oct 2003 Location: houston, texas Posts: 1,974	I would check them, however I dont have a manual for that and have no idea where those components are. __________________ 2008 Silverado Z71 RCSB 1991 GMC Jimmy 4x4 1976 GMC Sierra C15 SWB

04-27-2005, 09:33 PM	#7
screwballl Tonawanda 454 Join Date: Mar 2004 Location: Liquid Sunshine State Posts: 2,754	another idea.. the blower motor? also did you test with the unit's ground or ground to the body when testing?? when the fan is say on low is there voltage still getting to the blower itself? is there voltage and continuity immediately after the switch AND at the motor on all speeds? __________________ 91 Chevy Suburban Tonawanda 454 R2500 - SOLD!!! 04 Dodge Durango 5.7L Hemi 2WD, 24K miles (as of July 2011) In the past 30 years about 90% of Fords are still on the road, the other 10% made it home. -------------------

04-20-2005, 10:09 AM	#3
aggiedave98 Senior Member Join Date: Aug 2003 Location: Sugar Land, TX Posts: 1,007	but if it were the switch, I wouldn't get 12 volts at the resistor plug. When it's on high or off, I don't get 12 volts there. that's what I can't figure out.

04-25-2005, 02:03 PM	#5
aggiedave98 Senior Member Join Date: Aug 2003 Location: Sugar Land, TX Posts: 1,007	can you check the same things I checked: I finally decided to hunt it down (to find out it was really easy to find, but w/ the manuals you can never figure out where stuff is) and tested it. The resistors are in tack. I checked it w/ my ohm meter. There are actually 2 in series for some reason. I then tested the voltage at the plug for the resistor and when the rear blower is on low, I get 12 volts there. also just curious, but can you test the voltages at the different terminals of the resistor pack? thanks.

05-02-2005, 01:33 PM	#8
aggiedave98 Senior Member Join Date: Aug 2003 Location: Sugar Land, TX Posts: 1,007	hmmm.. well what I tested was just the voltage across the resistor pack itself... from one terminal to the other. I didn't take off the rear cover to get to the motor yet. But, since it works on high and the resistor seems to be working, I'm not sure... I guess I need to look at the full wiring diagram and put together what's going on... 88J, I'll try and get some pics of what I'm talking about... if you upen your hood on the passenger's side of the truck near the firewall, there is a housing there. On the right side of that housing (as you're facing the firewall) there is a wiring harness going into that black housing. There are 2 screws that take it off and you just slip the resistor pack out. Then you can test between the different terminals.



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