Greeting everyone!!
i have a questino regarding a very S-l-o-w heater . I have an 87 supra with a non funcitioning heater. The coolant is full and 50/50 . The VSV on the firewall for hte hot water from engin to go to heater is relatively new and working properely.
THe problem is it takes 15 min or now , its not even working to get warm. The ambietn sensor (in front of engin bay) is working correctly . I have not checked the internal sensor , but sicne it blows cold air in the summer , ti assume it works.
The auto speed control still delays its operation till the engine gets warm, but when it starts blowing , theere is NO WARM OR HOT AIR !! . I read about on another forum , he talked abvout the intgernal temp sensor , if it has a short or is open .... u will never get any warm air from the heater. this is what they said :
Because of the ECU’s design, when the cabin temp sensor is removed (unplugged, disconnected, an open circuit) the climate control ECU sees the cabin as being “infinitely cold” and puts the system into MAXIMUM HEAT, no matter what the dash controls are set to. And when the temp sensor is shorted, the ECU sees the cabin as being “infinitely hot” and puts the system into MAXIMUM COOL, again completely ignoring the dash settings. I learned this the hard way when I pulled out my center console to do some work - unplugging the temp sensor in the process - then had to go somewhere on a hot summer day. I about barbecued myself because the system blew hot air, no matter what I did.
So if the temperature sensor circuit has a short in it somewhere, you can play with the dash controls and all the stuff under the hood forever and you won’t get a bit of heat out of it. The quickest way I can think of to test it would be to remove the center console (the rear part, from just behind the gearshift back) and unplug the wires to the sensor. If you get heat, and lots of it, you have a shorted temp sensor. If you still don’t get heat, measure the resistance on the “car” side of the sensor’s plug to make sure you don’t have a short further up the internal wiring. You’ll need to check your manual for which two wires to measure between. If you definitely have an open circuit and STILL can’t get heat, you probably have a failure somewhere else in the electric part of the climate control. This could include broken wires going to the temperature flap servo, broken wires going to the ECU, or even a bad ECU.
So, does any of this make sense? I just want to have a list of things to check to get the HEATER TO WORK again!! I have serivce manual , but it doesnt have a rouble shooter sectino to test this climate control issue
kevin
i have a questino regarding a very S-l-o-w heater . I have an 87 supra with a non funcitioning heater. The coolant is full and 50/50 . The VSV on the firewall for hte hot water from engin to go to heater is relatively new and working properely.
THe problem is it takes 15 min or now , its not even working to get warm. The ambietn sensor (in front of engin bay) is working correctly . I have not checked the internal sensor , but sicne it blows cold air in the summer , ti assume it works.
The auto speed control still delays its operation till the engine gets warm, but when it starts blowing , theere is NO WARM OR HOT AIR !! . I read about on another forum , he talked abvout the intgernal temp sensor , if it has a short or is open .... u will never get any warm air from the heater. this is what they said :
Because of the ECU’s design, when the cabin temp sensor is removed (unplugged, disconnected, an open circuit) the climate control ECU sees the cabin as being “infinitely cold” and puts the system into MAXIMUM HEAT, no matter what the dash controls are set to. And when the temp sensor is shorted, the ECU sees the cabin as being “infinitely hot” and puts the system into MAXIMUM COOL, again completely ignoring the dash settings. I learned this the hard way when I pulled out my center console to do some work - unplugging the temp sensor in the process - then had to go somewhere on a hot summer day. I about barbecued myself because the system blew hot air, no matter what I did.
So if the temperature sensor circuit has a short in it somewhere, you can play with the dash controls and all the stuff under the hood forever and you won’t get a bit of heat out of it. The quickest way I can think of to test it would be to remove the center console (the rear part, from just behind the gearshift back) and unplug the wires to the sensor. If you get heat, and lots of it, you have a shorted temp sensor. If you still don’t get heat, measure the resistance on the “car” side of the sensor’s plug to make sure you don’t have a short further up the internal wiring. You’ll need to check your manual for which two wires to measure between. If you definitely have an open circuit and STILL can’t get heat, you probably have a failure somewhere else in the electric part of the climate control. This could include broken wires going to the temperature flap servo, broken wires going to the ECU, or even a bad ECU.
So, does any of this make sense? I just want to have a list of things to check to get the HEATER TO WORK again!! I have serivce manual , but it doesnt have a rouble shooter sectino to test this climate control issue
kevin
