Temperature selector

The AC and heat work fine, but only all cold or all hot. The temperature selector starts at 63 and has two degree intervals up to 80. At 63 it’s all AC and cold. If I move the selector to 65 it’s all hot with no gradations in between.

What is wrong?

Most likely a blend door that is stuck open to the heater core. Some Toyota’s are set up with a coolant valve that will let coolant flow to the heater core anytime the temp selector is set above the minimum 63 degrees. This allows the heater core to heat up. The blend door is used to regulate the temperature by diverting only a certain amount of air through the core to adjust the output air temp. But if the blend door is broken wide open, all the air goes through the hot heater core when the coolant flows through it.

If the temp selector is at minimum (63 deg), the coolant vale shuts flow of hot coolant to the core, and the heater core doesn’t get hot. This allows your A/C to blow full cold.

Thank you, Busted Knuckles. Yours is the first reply that makes sense and fits the symptoms.

I took the car to a local Toyota mechanic who said only that it was a computer problem and I should take it to the dealer. I did, and the dealer wanted $385 for an electronic diagnosis. Does that sound right?

It could be. The automatic climate control module controls the blend door. If it is not operating the blend door correctly, this may mimic a bad blend door. I just hate to advise you to pay $385 for an electronic diagnosis just to determine the root cause of your problem. Then, pay out the nose for the fix.

Thank you, sir.