Defogger Controls problems of the 1998 Toyota Avalon

1998 Toyota Avalon - without warning, the air conditioner/heater & fans quit working. This is intermittent. You never know when it is going to go out. This can be a safety issue if we are driving on the freeway, or anywhere for that matter, during a cold spell and the defroster suddenly goes off. Searching the internet there are numerous people with the same problem. . . . . And what is troubling is that Toyota is aware of it and has issued a technical service bulletin but even that you have to pull teeth to get a copy. In fact to get them to tell me there was an issue I had to tell them the tsa number I had found. They originally told me they had no information. They are not making this known to their customers.

The entire hvac system of the car shuts down. Blower, heater, defroster, a/c are all inoperative. Cannot be activated manually. Windshied quickly fogs. Hours or days later, operation returns to normal. Problem recurs without pattern.

Intermittent operation of automatic climate control system. No air conditioning, heater or fan operation. Complete shutdown of system. Will sometimes work after the car is turned off and restarted. This becomes very serious because front windshield will not defog. Toyota released a technical service bulletin on Dec. 3, 1999. Bulletin ac005-99 they knew that the system had a flaw so they redesigned and updated the (ecu) a/c amplifier. Its the brain for the complete heating and a/c system. I plead my case with the dealer and they said that they called Toyota and Toyota refused my request to have the parts and labor covered because of a bad design.

While driving, the entire climate control system failed without warning. Please provide additional information.