1987 toyota supra heater problems

Rob1 · 10-28-2009, 09:24 PM

i just replaced my heater control valve and my heat is still not working. i have fan motor bypassed with a switched 12v so i can turn it on cuz my factory control box would not turn it on but everything else on control box worked now with heat on full blast i get no heat only cold air. i would love to get my hands on a wireing diagram for he heat and air system for my 1987 toyota supra if anyone has one.

dannydavi · 10-28-2009, 11:04 PM

Dont know if this will help you, but when my heater was blowing cold air I by-passed my heater control valve, straight from back of head to firewall and worked great after that.

Busted Knuckles · 10-30-2009, 12:18 AM

Rob, does the valve open when the engine is running and the heat is on? The VSV is trouble-prone at this age. Run a vacuum line to by-pass the VSV straight to the valve. I did that, and now the valve opens. The VSV will open the valve anytime the temp setting is above 65 deg. Here's a site with pics:http://www.ddmcse.com/turbo/heatervs.htm

If the valve opens, then the problem is most likely with the blend doors under the dash that control the temperature. For directions to inspect and repair, check the TSRM:http://www.turboninjas.com/mk3supra/

suprabahamut · 11-19-2009, 04:39 AM

My heater core is clogged up from the previous owner pouring in radiator stop leak for now I use a harbor freight 12V heater. You should check it out they are only $9.

batmmannn · 06-17-2010, 07:31 AM

I would like to try this bypass but my car is an NA, I have no heat in my car. I looked at the link and then looked at my car. Here are a couple of pics, is the line in the second pic the one you connect to the top of the VSV and if so what do you do about the hole left where it was connected or do you T it off?

Please explain exactly what is done better than the person that made that post. Thanks, Scott

They appear to be using different lines in these two pics from two different posts to make the bypass.

Rob1 · 06-18-2010, 07:15 PM

I fixed mine. it turned out to be a problem with the heater control valve. i did the same thing they did on the picture with the blue vaccum lines. i used a T connector on a vacumm line on the driver side of the engine bay( cant remember exactly which one i sold the car) and used the extra port opened up by the T connector to run a vacumm line across the fire wall to the heater control valve. any vacumm line anywhere on the motor will work as long as its a constant vacumm. this will keep the valve open so there is always coolent running into the heater core therefore the heat is always ready for you when you hit the heat switch to open the door on the heater box.

10-28-2009, 09:24 PM	#1
Rob1 3" Exhaust Join Date: Aug 2009 Location: tennessee Posts: 137	1987 toyota supra heater problems i just replaced my heater control valve and my heat is still not working. i have fan motor bypassed with a switched 12v so i can turn it on cuz my factory control box would not turn it on but everything else on control box worked now with heat on full blast i get no heat only cold air. i would love to get my hands on a wireing diagram for he heat and air system for my 1987 toyota supra if anyone has one. __________________ My work in progress!!! 1989 toyota supra turbo targa top 7mgte, Five speed left hand drive. Last edited by Rob1; 10-28-2009 at 10:15 PM.

10-28-2009, 11:04 PM	#2
dannydavi 12psi boost Join Date: Mar 2007 Location: Sacramento, Ca Posts: 373	Dont know if this will help you, but when my heater was blowing cold air I by-passed my heater control valve, straight from back of head to firewall and worked great after that. __________________ '86.5 Supra - A/T - N/A - JDM Useful Sites: ToyoDIY.com ToyotaPart.com MKIIITSRM

06-17-2010, 07:31 AM	#5
batmmannn 12psi boost Join Date: May 2010 Location: West Virginia Posts: 320	By Pass I would like to try this bypass but my car is an NA, I have no heat in my car. I looked at the link and then looked at my car. Here are a couple of pics, is the line in the second pic the one you connect to the top of the VSV and if so what do you do about the hole left where it was connected or do you T it off? Please explain exactly what is done better than the person that made that post. Thanks, Scott They appear to be using different lines in these two pics from two different posts to make the bypass. Attached Thumbnails __________________ 1987 N/A 7MGE Left Hand Drive MK3 Red 5 Speed and Black Auto Supras My Next project is the Batmobile! Last edited by batmmannn; 06-17-2010 at 07:51 AM.

06-18-2010, 07:15 PM	#6
Rob1 3" Exhaust Join Date: Aug 2009 Location: tennessee Posts: 137	I fixed mine. it turned out to be a problem with the heater control valve. i did the same thing they did on the picture with the blue vaccum lines. i used a T connector on a vacumm line on the driver side of the engine bay( cant remember exactly which one i sold the car) and used the extra port opened up by the T connector to run a vacumm line across the fire wall to the heater control valve. any vacumm line anywhere on the motor will work as long as its a constant vacumm. this will keep the valve open so there is always coolent running into the heater core therefore the heat is always ready for you when you hit the heat switch to open the door on the heater box. __________________ My work in progress!!! 1989 toyota supra turbo targa top 7mgte, Five speed left hand drive.

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10-30-2009, 12:18 AM	#3
Busted Knuckles 12psi boost Join Date: Dec 2007 Location: Atlanta Posts: 300	Rob, does the valve open when the engine is running and the heat is on? The VSV is trouble-prone at this age. Run a vacuum line to by-pass the VSV straight to the valve. I did that, and now the valve opens. The VSV will open the valve anytime the temp setting is above 65 deg. Here's a site with pics:http://www.ddmcse.com/turbo/heatervs.htm If the valve opens, then the problem is most likely with the blend doors under the dash that control the temperature. For directions to inspect and repair, check the TSRM:http://www.turboninjas.com/mk3supra/

11-19-2009, 04:39 AM	#4
suprabahamut 3" Exhaust Join Date: May 2007 Location: greensboro Posts: 242	My heater core is clogged up from the previous owner pouring in radiator stop leak for now I use a harbor freight 12V heater. You should check it out they are only $9.