88 Camry no heat

My 88 Camry heater does not work, only cold air blowing. I have checked the shutoff valve in the engine compartment and its closed, when I disconnect the cable and move it to open still no heat, both hoses are hot. Seems like a door/flapper under the dash is not opening to supply heat from the heater core. I have the electronic dash and don't know how the system works and I cant open the door manually.
Do I need a new heater control module or ?
Any advice would be greatly appreciated.

Thanks in advance

My 87 is doing the same thing and like you at one time thought the valve was bad. Not the case. Sometimes cycling the temp control gives me heat but thats rare. If I force and hold the switch up or down I get heat just about every time but, doing that all the time isn't practical. The temp switch actuates the blend door motor at the very front bottom of the climate control pack near the firewall. I can watch it cycle back to cold on it's own after moving the temp switch to hot. I just need to take the time to get at the control panel and the temp control switch try fixing it. Keep in touch.

I have removed the switch control module, the back has a electrical plug and circuit board, didnt see anything wrong. So I sprayed some electrical contact cleaner onto slider control and seems to free up the sliding motion alot better, could of been dirty or worn, it is now working again. The control switch seems like a resistor or amplifiar type circuit, wonder if this can be replaced.

Anything can be replaced, but you may have to buy the whole control switch. You will have to check with a Toyota dealer's parts department for that information. If it's too espensive at the dealer a salvage yard would probably be your only other choice. However, if it's working properly now I would just leave things alone.

Mike