My 1993 Previa LE heat has stopped working. Haven't used heat all
summer, now weather's cooling and can't get any heat to come out! A/C
works fine (although mildly noisy ringing sometimes). Any ideas on what
to check? Could it be as simple as replacing the thermostat? We need the heat soon!
thanks
If there is a leak in the watercycle and the water level drops below a certain level the heating will not work.
The solution is to detect the leak and to replace the relevant problem part.
Thanks for the quick reply. What you have is a thremostat that is stuck in the "open" position. This would explain why the temp gauge reads low. Also, this condition will also cause the engine to seem like it is "revving up". Why? Because the OverDrive will not engage until the temperature of the coolant is 172 degrees F. When the coolant reaches that temp, the OD solenoid gets power from the ECU, dependant on the temp mentioned above...NOW, when the temp of the coolant DROPS below 172 (as in having a seized open thermostat), the solenoid is de-energized by the ECU, and the trans shifts OUT of OD. Downshifting to the next lower gear cause the RPMs to incerase. In any case, replace the thermostat, and whilst you are doing this, replace the coolant, also. If you have RED coolant, that is factory Toyota coolant. Is is a GOOD IDEA to continue using the red coolant if you already have it in your cooling system. Buy the stat and the coolant at a Toyota dealer. Do NOT buy an "aftermarket" stat. The cheaper ones do NOT have the air "wiggle" valve built into the stat. Install the stat with the little "wiggle valve" pointing straight up; "12 o'clock". Add 50-50 coolant water mix, Bleed the air from the cooling system & you will be fine.
Make sure that you use a 50-50 mix, and make sure that all of the air is out of it before you take off.
...the temp gauge should read at 1/2 of the way up. If you have air in it, the gauge will be higher.
Thanks for the Fix Ya. Much appreciated.
If the stat was letting the fluid stay at 175 degrees, the OD would function, but you would still have no heat. You need at least 185 degrees temp to get minimal heat. Try this: Get a thermometer. put it in the rad cap hoel & start the engine. Note the temp when the gauge reaches 1/2, and get that info back to me.
Thanks for the FixYa. Much appreciated. Do keep the appointment, though. Your heat is back because your t'stat is obviously sticking, and you do NOT want it to stick in the "closed" position.You will def overheat the engine. A new stat and a flush are very good choices for you. Thanks again for allowing me to help.
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Yes it has a temp. gauge, and my wife did notice yesterday the gauge seemed to drop very low after driving for a while. She also noticed the engine was revving higher than normal at idle, but I don't know if that's due to cooler weather or it's part of the problem.
Ed - thanks for the in-depth assessment, much appreciated. Picking up an OEM stat, gasket and coolant at Toyota tomorrow. One more thing - haven't replaced coolant in the Previa before - any tips for doing this?
thank you!
Ed - didn't get a chance to replace the thermostat yet, but noticed driving the van this weekend the temp gauge does go up about 1/2 way, and O/D is working; still no heat though. Is it still possible the thermostat is the problem?
Finally got a chance to look at my van, and realized very quickly this isn't a job I want to tackle. Called my Toyota mechanic today, no problem, should only take 30-40mins., he can do it Friday (using the parts I already bought). So tonight I was driving the van....and the heat works! Very strange.
Think I'll keep the appt. and just get a rad flush and replace the thermostat anyway, not an expensive part. Go figure though.
i have not alot of heat coming out of the blower air con is fine the dial on the dash reads cool even when i have been for a long drive.
Do you have a temperature gauge? If so, where is the needle when you are driving?
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