I think what you mean is that the blend air door is not functioning properly. Its job is to switch the flow of air between A/C and the heater core. If that is what the problem is, you may be able to bypass the heater core.
The heater core is basically a miniature radiator. Hot engine coolant goes into the heater core. The blower blows air through the system. That air is directed to run through the heater core by the blend air door. The result is (1) warm air comes out of the core and goes through your vents and (2) your engine coolant is slightly cooler than it was.
That is a very basic overview of how it works. So if you take the hose that goes into the heater core, and hook it up to the hose that's coming out of the core, you will be bypassing the core completely.
Use this guide to drain your cooling system: https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars.
Next, you should see two hoses going into the firewall (that is the wall between the engine and the cabin. They should be closer to the passenger side of the vehicle. When the engine is cold, loosen the clamp on one of those hoses. Trace that hose to its other end and remove it as well. Take that hose to the local Home Depot or Lowe's store, go to the plumbing department, and get a plumbing elbow or something so you can link the two hoses together. Then just install that piece to connect the hoses, make sure that your hoses are secure and that the clamps are tight.
You will need to add some coolant to the system. Here is a guide for that: https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars
Start at step 5.
Good luck and let us know how it goes.
Wednesday, July 12th, 2017 AT 2:13 PM