Factory A/C & Heater Help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

big dump · 07-30-2008, 07:14 PM

Turned on the A/C the other day and started getting a bunch of smoke from under the dash. Figured it was probably the electric switch on the controls so took it apart and found a few issues. First picture shows the burned up switch, second picture shows burned up compressor clutch wiring, third picture shows the high speed blower relay, forth picture shows the outside of the blower motor assembly with a mystery hose that's cracked.

Two questions, first of all, should the relay be mounted to the firewall, or is a remote ground sufficient? Secondly, what is the hose in the forth picture, and where can I get a new one? I haven't been able to find anything online about it, am I going to have to just get a plug fitting and new hose? Anyone know what it's called, and what it's for?

Thanks,

JimKshortstep4x4 · 07-30-2008, 07:56 PM

The relays are normally mounted on the inside heater box with a remote ground so what you have should work.

The hose pictured is to circulate air through the blower motor. From looking at the picture it does not look too bad. Does the blower motor have a hole in it for the flanged end of the hose?

Jim

Andy4639 · 07-30-2008, 08:42 PM

From the pictures posted you look like it grounded out on something. Has any of the wires got bare spots on them? Something caused the wire insulator & plug in to melt. The hose and motor should be as one. The motor needs the hole for the hose to go into all it does is let air pass through to the motor. This helps it keep cool and burning the motor up.

big dump · 07-31-2008, 09:33 AM

Thanks for the input guys. Jim, the hose is actually cracked, it looks like from the picture that the hose is still somewhat intact, however it's actually broken off and the molded end (flanged end) is still in the hole in the blower motor. Anyone know where I can track a new one down? As far as the wiring, I think that I'm going to create a dedicated ground somewhere on the firewall, because I think that's what led to the whole burn up.

jayharrell · 07-31-2008, 01:38 PM

Looks like your missing the 4th wire on the AC switch too. That give you your low, mid, high setting. I have the ac wiring diagram on my pc at home.

I might have a good hose at the house, i'll look when i get home. I'll drop it in the mail for yah if its good.

ChevLoRay · 07-31-2008, 04:23 PM

Another reason to replace my A/C wiring harness.....

big dump · 07-31-2008, 05:12 PM

Appreciate the help Jay. Yeah, I think you're right about the 4th wire. I need to check out a diagram and go from there. Definately one reason to completely go through the wiring in these oldies and update. Thanks for the help guys...

big dump · 07-31-2008, 05:14 PM

BTW, anyone know of any good online places to get wire pigtails for older style switches like in our trucks? i.e. 4 pin A/C control switch, 2 pin Compressor clutch, etc. I'd like to put all new connectors on these and would prefer to use factory style rather than just spade connectors and electrical tape.

jayharrell · 08-02-2008, 10:55 AM

Well i didn't have the motor cooling hose, but heres a diagram.

mrein3 · 08-02-2008, 11:13 AM

Quote:

Originally Posted by big dump

BTW, anyone know of any good online places to get wire pigtails for older style switches like in our trucks? i.e. 4 pin A/C control switch, 2 pin Compressor clutch, etc. I'd like to put all new connectors on these and would prefer to use factory style rather than just spade connectors and electrical tape.

Here is what I would do (and actually did do a few years ago):
First I ordered a new switch and a new plastic connector for the back of the switch from LMC. Folks here hate LMC. If you don't like them find a board sponsor and see if they carry these pieces. I didn't have to order the 2-pin compressor connector so I don't know if they are available. If not just go to the junk yard and clip one off a donor. Then go to NAPA and order "type 56" connectors. At NAPA they won't know what you are talking about so just tell them you want 20 or so pieces of part number 725147. The male side of that connector is 725145. You may as well grab some of those too. Buy extras because most of the connectors in your truck have this brass colored insert for the actual connection. I keep a handfull of both around my shop. Then go to Lowe's, Home Depot, Menard's, your local hardware store, where ever and purchase spools of the correct color wire.

Once you got all that stuff just make your own wires. Notice the wiring diagram jayharrell posted. It tells you exactly what color and gauge of wire you need. If you didn't know, 14Y = 14 gauge yellow. 14DBL = 14 gauge dark blue, etc.

I hope this helps.

big dump · 08-05-2008, 12:59 PM

Thanks for the diagram, and I also appreciate the part numbers. I'm gonna give that a go for the next step. I'll keep posted...

big dump · 08-26-2008, 01:17 PM

Got pretty much everything all fixed up, replaced all the bad wiring, made new solid grounds for everything, replaced all the vacuum lines, etc. Now I'm having an issue with the factory wiring diagram. On the diagram, the clutch green wire, and 14ga yellow wire from the control switch go to a 'compressor switch' (circled in picture).

The problem is, I don't have anything on the back of the A/C controls that these wires can connect to. Where is this 'compressor switch' supposed to be mounted? Does anyone have a picture? Also, my harness does not have the anti-dieseling wiring, that shouldn't have anything to do with the 'compressor switch' wiring anyway, right? Thanks,

jayharrell · 08-26-2008, 03:33 PM

Thats the difference between the diagrami posted and the one you have. The anti dieseling deal is more of a saftey add on deal. Supose to keep the clutch on the compressor locked for about 5 seconds after the key is turned off to keep the moter from jumping up after the key is off due to the new HP from the compressor being uncluchted. If that makes sense. mine didn't have it, so i went with the non dieseling diaghram.

But i'll get a picture of the compressor switch. its on the back of the dirvertor. There is supose to be a switch that attaches to the back of the divertor box, its actuated by a cam on the divertor itself. When you move the controlls to AC, it pushes that switch.

big dump · 08-27-2008, 09:54 AM

Yeah, I'm pretty sure that I don't have that switch on the divertor box. If you could post a picture, that would really help out.

Thanks,

**steelhorse** · 08-27-2008, 10:02 AM

Most cars and trucks have the blower motor hose that is cracked on yours.Just go to a junkyard and find one that is close enough to fit if you cant order one.

big dump · 08-27-2008, 02:15 PM

Thanks for the tip, I'll check into a couple yards around here.

jayharrell · 08-27-2008, 03:30 PM

i couldn't get a picture of my box last night, but found this pic. The bracket on top there should have a switch on it. Hope that helps

07-30-2008, 07:14 PM	#1
big dump Registered User Join Date: Mar 2006 Location: Gilbert, AZ Posts: 179	Factory A/C & Heater Help Turned on the A/C the other day and started getting a bunch of smoke from under the dash. Figured it was probably the electric switch on the controls so took it apart and found a few issues. First picture shows the burned up switch, second picture shows burned up compressor clutch wiring, third picture shows the high speed blower relay, forth picture shows the outside of the blower motor assembly with a mystery hose that's cracked. Two questions, first of all, should the relay be mounted to the firewall, or is a remote ground sufficient? Secondly, what is the hose in the forth picture, and where can I get a new one? I haven't been able to find anything online about it, am I going to have to just get a plug fitting and new hose? Anyone know what it's called, and what it's for? Thanks,

07-30-2008, 07:56 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Factory A/C & Heater Help The relays are normally mounted on the inside heater box with a remote ground so what you have should work. The hose pictured is to circulate air through the blower motor. From looking at the picture it does not look too bad. Does the blower motor have a hole in it for the flanged end of the hose? Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

07-30-2008, 08:42 PM	#3
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: Factory A/C & Heater Help From the pictures posted you look like it grounded out on something. Has any of the wires got bare spots on them? Something caused the wire insulator & plug in to melt. The hose and motor should be as one. The motor needs the hole for the hose to go into all it does is let air pass through to the motor. This helps it keep cool and burning the motor up. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

07-31-2008, 09:33 AM	#4
big dump Registered User Join Date: Mar 2006 Location: Gilbert, AZ Posts: 179	Re: Factory A/C & Heater Help Thanks for the input guys. Jim, the hose is actually cracked, it looks like from the picture that the hose is still somewhat intact, however it's actually broken off and the molded end (flanged end) is still in the hole in the blower motor. Anyone know where I can track a new one down? As far as the wiring, I think that I'm going to create a dedicated ground somewhere on the firewall, because I think that's what led to the whole burn up.

07-31-2008, 01:38 PM	#5
jayharrell Gettin By on Gettin By Join Date: Jan 2008 Location: Cedar Creek, Tx Posts: 1,033	Re: Factory A/C & Heater Help Looks like your missing the 4th wire on the AC switch too. That give you your low, mid, high setting. I have the ac wiring diagram on my pc at home. I might have a good hose at the house, i'll look when i get home. I'll drop it in the mail for yah if its good. __________________ 69 CST10 LWB 455 Buick 00 S10 2.2 Vin5 76 GL1000 Naked 1bl VW carb "Adios to all the concrete; Gonna get me some dirt road back streets"

07-31-2008, 04:23 PM	#6
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: Factory A/C & Heater Help Another reason to replace my A/C wiring harness..... __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

07-31-2008, 05:12 PM	#7
big dump Registered User Join Date: Mar 2006 Location: Gilbert, AZ Posts: 179	Re: Factory A/C & Heater Help Appreciate the help Jay. Yeah, I think you're right about the 4th wire. I need to check out a diagram and go from there. Definately one reason to completely go through the wiring in these oldies and update. Thanks for the help guys...

07-31-2008, 05:14 PM	#8
big dump Registered User Join Date: Mar 2006 Location: Gilbert, AZ Posts: 179	Re: Factory A/C & Heater Help BTW, anyone know of any good online places to get wire pigtails for older style switches like in our trucks? i.e. 4 pin A/C control switch, 2 pin Compressor clutch, etc. I'd like to put all new connectors on these and would prefer to use factory style rather than just spade connectors and electrical tape.

08-02-2008, 10:55 AM	#9
jayharrell Gettin By on Gettin By Join Date: Jan 2008 Location: Cedar Creek, Tx Posts: 1,033	Re: Factory A/C & Heater Help Well i didn't have the motor cooling hose, but heres a diagram. Attached Images __________________ 69 CST10 LWB 455 Buick 00 S10 2.2 Vin5 76 GL1000 Naked 1bl VW carb "Adios to all the concrete; Gonna get me some dirt road back streets"

08-05-2008, 12:59 PM	#11
big dump Registered User Join Date: Mar 2006 Location: Gilbert, AZ Posts: 179	Re: Factory A/C & Heater Help Thanks for the diagram, and I also appreciate the part numbers. I'm gonna give that a go for the next step. I'll keep posted...

08-26-2008, 01:17 PM	#12
big dump Registered User Join Date: Mar 2006 Location: Gilbert, AZ Posts: 179	Re: Factory A/C & Heater Help Got pretty much everything all fixed up, replaced all the bad wiring, made new solid grounds for everything, replaced all the vacuum lines, etc. Now I'm having an issue with the factory wiring diagram. On the diagram, the clutch green wire, and 14ga yellow wire from the control switch go to a 'compressor switch' (circled in picture). The problem is, I don't have anything on the back of the A/C controls that these wires can connect to. Where is this 'compressor switch' supposed to be mounted? Does anyone have a picture? Also, my harness does not have the anti-dieseling wiring, that shouldn't have anything to do with the 'compressor switch' wiring anyway, right? Thanks,

08-26-2008, 03:33 PM	#13
jayharrell Gettin By on Gettin By Join Date: Jan 2008 Location: Cedar Creek, Tx Posts: 1,033	Re: Factory A/C & Heater Help Thats the difference between the diagrami posted and the one you have. The anti dieseling deal is more of a saftey add on deal. Supose to keep the clutch on the compressor locked for about 5 seconds after the key is turned off to keep the moter from jumping up after the key is off due to the new HP from the compressor being uncluchted. If that makes sense. mine didn't have it, so i went with the non dieseling diaghram. But i'll get a picture of the compressor switch. its on the back of the dirvertor. There is supose to be a switch that attaches to the back of the divertor box, its actuated by a cam on the divertor itself. When you move the controlls to AC, it pushes that switch. __________________ 69 CST10 LWB 455 Buick 00 S10 2.2 Vin5 76 GL1000 Naked 1bl VW carb "Adios to all the concrete; Gonna get me some dirt road back streets" Last edited by jayharrell; 08-26-2008 at 03:34 PM.

08-27-2008, 09:54 AM	#14
big dump Registered User Join Date: Mar 2006 Location: Gilbert, AZ Posts: 179	Re: Factory A/C & Heater Help Yeah, I'm pretty sure that I don't have that switch on the divertor box. If you could post a picture, that would really help out. Thanks,

08-27-2008, 10:02 AM	#15
steelhorse Senior Member Join Date: Apr 2008 Location: Franklinton NC Posts: 1,309	Re: Factory A/C & Heater Help Most cars and trucks have the blower motor hose that is cracked on yours.Just go to a junkyard and find one that is close enough to fit if you cant order one.

08-27-2008, 02:15 PM	#16
big dump Registered User Join Date: Mar 2006 Location: Gilbert, AZ Posts: 179	Re: Factory A/C & Heater Help Thanks for the tip, I'll check into a couple yards around here.



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08-27-2008, 03:30 PM	#17
jayharrell Gettin By on Gettin By Join Date: Jan 2008 Location: Cedar Creek, Tx Posts: 1,033	Re: Factory A/C & Heater Help i couldn't get a picture of my box last night, but found this pic. The bracket on top there should have a switch on it. Hope that helps Attached Images __________________ 69 CST10 LWB 455 Buick 00 S10 2.2 Vin5 76 GL1000 Naked 1bl VW carb "Adios to all the concrete; Gonna get me some dirt road back streets"

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