Car air conditioning systems that blow warm on one side and cold on the other side usually have one of two problems. In this short auto repair article, a master automotive technician shares his experience, derived from working on air conditioners in Florida for the last couple of decades. This free information can be equally helpful to the do-it-yourselfer as it is to a consumer that knows the value of being informed when it comes to dealing with car repair shops. Read on for free car A/C help when the air is blowing warm on ONE side.
Usually cars that blow cold on one side of the dash and warm on the other side, are typically equipped with a dual zone climate control system. Dual zone systems allow the driver and front passenger to adjust respective temperatures to their comfort levels. There are two common causes of a temperature difference when both sides are set at the coldest settings, lets cover the first one.
Automotive air conditioners which use 134A, usually hold a small amount of refrigerant compared to older automobiles that use R12. Car and truck air conditioners today are much more efficient than their older counter parts. The fact that 134A systems use less freon, means that a leak can more quickly affect the performance of an HVAC (Heating Ventilation & Air Conditioning) system. Due to the design of dual AC systems, low refrigerant is the leading cause of drastic temperature difference from one side of the dash to the other. Even well experienced car mechanics may be surprised to learn that as little as 4 to 8 ounces undercharged of 134A can make such a huge difference. The temperature from the left vent to the right vent can vary 10 to 20 degrees. The easiest thing to try is to top off the system or better yet, remove all freon and recharge the unit with the factory specified amount. In most cases after the proper charge of Freon is in the car, the temp will blow equally as cold like it should on BOTH sides!
What if that didn’t help? Read on to learn of another possible cause of the problem.
HVAC Door Issue
Dual zones supplying different temperatures from vents on either side of the dash is achieved by the use of small doors within the HVAC housing. By controlling the doors, the temperature of the air on the left and right can be adjusted to the desired comfort level. Many times the motor (or actuator) that controls the door for either side can fail or the door itself can break and prevent the temp. from being adjusted. Diagnosing this problem is more complex and can be a subject for another article. Thanks for reading. Hopefully, the free information provided here will help to remedy the problem of “AC’s blowing hot or warm from one side of the dash.”