My Car AC is Blowing Hot Air

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My Car AC is Blowing Hot Air

gp-2nothing worse than climbing into your car on a hot day, turning on the air conditioner, and finding that it only blows hot air. There are several reasons for your air conditioning unit to fail. Here are four of the most common:

  1. The refrigerant in your AC unit needs to be recharged.
  2. The AC Compressor isn’t working.
  3. The refrigerant circuit is blocked, so it’s not circulating refrigerant inside the unit.
  4. The blend air door inside the HVAC unit is stuck on HEAT, so air isn’t circulating through the evaporator.

The problem can be diagnosed by checking a few things:

The Compressor

gp-3When you turn on the AC, does the compressor start? If so, the good news is that it’s working. The bad news is that your problem may be that the blend air door is stuck and the motor that controls it needs to be replaced. This repair is tricky; you’ll want to see a professional mechanic.

If the compressor doesn’t start, your mechanic can perform a few tests to see if you need to replace the compressor clutch, recharge the refrigerant, or replace the entire compressor.


Your mechanic can hook an AC pressure gauge to the pressure hose that runs between the compressor and the condenser to see if you have adequate refrigerant. If not, he’ll get all the air out of the AC system, then recharge the unit with the correct amount of refrigerant.

Orifice Tube

The orifice tube is positioned between the condenser and the evaporator. If it’s blocked, refrigerant isn’t able to reach the evaporator. As a result, the unit will blow only warm or hot air.

Dual Zone Climate Control System

This popular feature allows the passenger of the car to set his controls to a different temperature than that of the driver. Unfortunately, sometimes parts in that system break, which can cause the AC to blow only hot air. Your mechanic can check the dual zone climate control system to ensure that an HVAC door isn’t stuck.

gp-4Find a Professional to Help

Your car’s air conditioning unit is difficult to repair by yourself; it’s best to hire a professional mechanic to address the issue. Tearing apart an AC unit, fixing a problem and reassembling the unit can take a mechanic as long as 8-10 hours.

You can’t recharge your car’s AC unit with refrigerant unless you are certified; to purchase the refrigerant you must show proof of certification. Refrigerant is regulated by the EPA (Environmental Protection Agency), because it depletes the ozone. Technicians must be certified to work with it and to meet all EPA standards for recycling.




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