Resistor-Dumb question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

treefrog · 08-30-2003, 09:08 AM

I pulled the heater/AC control to replace the fan switch. I also replaced the relay behind the glove box. Vendor said to replace the resistor at the same time. Where is it? Told you it was a dumb question. TF

Class of 69 · 08-30-2003, 09:21 AM

I think they are the same part, just different names for it. If the relay you replaced is on top of the heater box with 2 orange, 1 yellow, and 1 light blue wires to it, then that IS the resistor, which is also a relay...it controls the fan speeds.

treefrog · 08-30-2003, 09:37 AM

69 - The one behind the glove box was a sealed unit. It has 2 orange, one purple, 1 green, and a ground. If there are only 2 controls, the switch and the one I put in, then this is a third unit, no wonder I can't find it. Are there 2 controls or 3?
TF

Class of 69 · 08-30-2003, 09:51 AM

Doesn't sound like the resistor that you replaced. I missed the fact that you had A/C. Yes, there a 3 controls with A/C. The resistor is on top of the heater box with just the wire connector showing. The actual resistor is inside, held in by 2 small screws. If this isn't enough help, I will take a pic when I get my lazy butt out to the shop.

GMC Jim · 08-30-2003, 10:14 PM

There are 2 relays and 1 resistor pack used with the Chev/GMC Four seasons air conditioning system....The blower motor relay is up underneath next to the outside top right hand side of glovebox. This relay has 5 wires total. Black ( ground); Purple (to blower motor); Orange ( to fuse panel); Dark Blue ( to resistor pack) and another Orange (18 guage) (to control switch)
The anti-dieseling relay is located on back side of instrument panel ; just to the left of the heater/air cond control. relay activates the air cond. compressor when the ignition is turned off ( to prevent after-run. This relay has 3 wires; Orange ( to blower motor relay); Pink ( to control switch) and Dark Green ( to compressor switch. Note:- my 1971, 402 engine does not have this anti-dieseling relay... possible former owner removed as it did cause some problems, I understand.
The resistor pack is located within the lower duct work.. To access; remove the screw attaching the floor outlet duct to the firewall. Thenremove the screws attaching the air distribtion box to the heater case. Slide this portion of the box downward and out of the way letting it rest on the floor panel. You should see the wires going to the plug to the resistor pack. There are 3 wires ; Yellow ( to control switch); Dark Blue ( to blower motor relay) and Light Blue ( to control switch)
This info is from the GM service manual........... Jim ( Hope it helps ! )

GMC Jim · 08-30-2003, 10:18 PM

TF.... There is really no need to replace the resistor pack....if the fan switch operates properly ; dropping the fan speed with each "click"....!!!

Longhorn Man · 08-30-2003, 11:25 PM

And dropping the plenum is not really needed. I just replaced mine in the longhorn about 2 weeks ago.

treefrog · 08-31-2003, 07:12 AM

I don't know how this got posted on 2 threads, advanced senior moment I suppose, but I'm dupicating the reply so as not to miss thanking you all for the help. From the drawing 5150 sent and the directions from Jim, it is now all over the floor.

I will hold the drawing in front of a mirror to reverse the image when I try to get it back together this afternoon. If I get it together and it works, its miracle time in Tennessee. Thanks again, TF

08-30-2003, 09:08 AM	#1
treefrog Registered User Join Date: May 2002 Location: Knoxville, TN USA Posts: 189	Resistor-Dumb question I pulled the heater/AC control to replace the fan switch. I also replaced the relay behind the glove box. Vendor said to replace the resistor at the same time. Where is it? Told you it was a dumb question. TF

08-30-2003, 09:21 AM	#2
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	I think they are the same part, just different names for it. If the relay you replaced is on top of the heater box with 2 orange, 1 yellow, and 1 light blue wires to it, then that IS the resistor, which is also a relay...it controls the fan speeds. __________________ 69 GMC K10 ..some restoration required....still..

08-30-2003, 09:37 AM	#3
treefrog Registered User Join Date: May 2002 Location: Knoxville, TN USA Posts: 189	Relay 69 - The one behind the glove box was a sealed unit. It has 2 orange, one purple, 1 green, and a ground. If there are only 2 controls, the switch and the one I put in, then this is a third unit, no wonder I can't find it. Are there 2 controls or 3? TF

08-30-2003, 09:51 AM	#4
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	Doesn't sound like the resistor that you replaced. I missed the fact that you had A/C. Yes, there a 3 controls with A/C. The resistor is on top of the heater box with just the wire connector showing. The actual resistor is inside, held in by 2 small screws. If this isn't enough help, I will take a pic when I get my lazy butt out to the shop. __________________ 69 GMC K10 ..some restoration required....still..

08-30-2003, 10:14 PM	#5
GMC Jim Senior Member Join Date: Dec 2002 Location: Portland, Oregon Posts: 901	There are 2 relays and 1 resistor pack used with the Chev/GMC Four seasons air conditioning system....The blower motor relay is up underneath next to the outside top right hand side of glovebox. This relay has 5 wires total. Black ( ground); Purple (to blower motor); Orange ( to fuse panel); Dark Blue ( to resistor pack) and another Orange (18 guage) (to control switch) The anti-dieseling relay is located on back side of instrument panel ; just to the left of the heater/air cond control. relay activates the air cond. compressor when the ignition is turned off ( to prevent after-run. This relay has 3 wires; Orange ( to blower motor relay); Pink ( to control switch) and Dark Green ( to compressor switch. Note:- my 1971, 402 engine does not have this anti-dieseling relay... possible former owner removed as it did cause some problems, I understand. The resistor pack is located within the lower duct work.. To access; remove the screw attaching the floor outlet duct to the firewall. Thenremove the screws attaching the air distribtion box to the heater case. Slide this portion of the box downward and out of the way letting it rest on the floor panel. You should see the wires going to the plug to the resistor pack. There are 3 wires ; Yellow ( to control switch); Dark Blue ( to blower motor relay) and Light Blue ( to control switch) This info is from the GM service manual........... Jim ( Hope it helps ! ) __________________ '71 GMC;fleetside;PB/PS/AC/CC/402 Eng./Custom Paint/110,000act miles/3 fuel tanks(52gal).

08-30-2003, 10:18 PM	#6
GMC Jim Senior Member Join Date: Dec 2002 Location: Portland, Oregon Posts: 901	TF.... There is really no need to replace the resistor pack....if the fan switch operates properly ; dropping the fan speed with each "click"....!!! __________________ '71 GMC;fleetside;PB/PS/AC/CC/402 Eng./Custom Paint/110,000act miles/3 fuel tanks(52gal).

08-30-2003, 11:25 PM	#7
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	And dropping the plenum is not really needed. I just replaced mine in the longhorn about 2 weeks ago.

08-31-2003, 07:12 AM	#8
treefrog Registered User Join Date: May 2002 Location: Knoxville, TN USA Posts: 189	I found it I don't know how this got posted on 2 threads, advanced senior moment I suppose, but I'm dupicating the reply so as not to miss thanking you all for the help. From the drawing 5150 sent and the directions from Jim, it is now all over the floor. I will hold the drawing in front of a mirror to reverse the image when I try to get it back together this afternoon. If I get it together and it works, its miracle time in Tennessee. Thanks again, TF



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