Which parts fail
Components named in complaints (air conditioning, heater, defroster, HVAC controls).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 1998 Toyota Avalon owners, lightly cleaned up (personal details are redacted by NHTSA).
At 49,000 miles, the entire air conditioning system failed. Both the compressor and the condensor have leaks and the whole system must be replaced. Toyota has failed to offer any goodwill assistance for this repair which costs in excess of $ 1200.00 simply claiming "its out of warranty." all this is a "luxury, flagship" vehicle. Don't buy this car! Toyota customer service stinks!! They are alot of talk about reputation but they fail to live up to their promises!! I am very dissatisfied with this car! Additionally, my mechanic has told me that he has several avalons with this same problem which he will be repairing. Toyota fails to accept it is a manufacturing defect in their air conditioning parts!
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.
A/C climate control shuts itself off automatically after a short period usage. The outside temperatur eindicator,fan speed,ventilation direction, and outside air recirculation controls all go out. Almost gotten into an accident when the windshield A/C defrost did not work due to this problem. Still under the milage warranty(>36000), and went to Toyota dealer and was quoated $900 to get this problem fixed. Will contact Toyota customer service next.
A/C climate control shuts itself off automatically after a short period usage. The outside temp.indicator,fan speed,ventilation direction, and outside air recirculation controls all go out. Almost gotten into an accident when the windshield A/C defrost did not work due to this problem. Still under the milage warranty(>36000), and went to Toyota dealer and was quoated $900 to get this problem fixed. Will contact Toyota customer service next.
On a 98 Toyota Avalon xls: the A/C and heating system shuts down completely occasionally. The front and rear defoggers fail also. When the shut down occurs, the air vents emit very hot air, even though the thermostat is set for A/C. I almost had an accident when it started raining and the defoggers failed to operate. It appears to be an electrical wiring defect for which I have appealed to Toyota to take responsibility,but without any success
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.
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 automatic climate control system (heating & ac) cuts out arbitrarily. It restarts after the car has been sitting idle for some time. This has caused several problems as the front windshield will not defog and vision through the windshield is impaired. This compromises my vision and has put me in danger several times. When contacted dealer, they mentioned that there is no recall on this dangerous problem and that the repair will cost ~$1,000. This is a serious hazard.
The automatic air conditioner and the ambient temperature failed. There blower motor does not work. Contacted Toyota who informed me that there is a TSB which essentially admits that there was a faulty servo installed in this car but Toyota will not pay for a repair of a problem that was a direct result of their poor quality control. They have quoted this repair to be at about one thousand dollars to correct their problem.
While vehicle is underway, automatic climate control system arbitrarily cuts off and cannot be restarted automatically or manually. This leaves the vehicle without A/C, fan ventilation or front window defogging capability. The absence of defogging, in particular, is a safety hazard because window can fog up quickly on hot, humid rainy days and severely compromise driver visibility.
AC & Heater complaints in other Avalon years
Frequently asked questions
How common are ac & heater problems on the 1998 Toyota Avalon?
NHTSA has 25 complaints about the a/c & heater of the 1998 Toyota Avalon, 14% of the model year's 178 complaints. The component named most often is appliance › air conditioner (14 mentions).
Is there a recall for 1998 Toyota Avalon ac & heater problems?
No. NHTSA lists no a/c & heater recall for the 1998 Toyota Avalon, though it has 1 recall for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 1998 Toyota Avalon ac & heater problems start?
Half of the complaints with a recorded mileage happened before about 49,000 miles, and 20% before 25,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.