Posts Tagged ‘A/C’


Why Did My Belt Melt?


The other day, the v-belt started smoking and eventually burned right through.  I fitted a new one and the exact same thing happened.  Any idea what might be causing this?

Colleen P., TX


Sounds to me like something is seized up.  First thing you should do is try to turn everything on the belt path by hand.  I’m willing to bet that the AC compressor is the guilty party.

If so, there are two things you can do.  You can get the compressor checked out to see if it can be fixed or needs to be replaced.  If you’re looking to save a few bucks and don’t need AC immediately, you can get a shorter belt that will bypass the AC compressor allowing you to drive the car normally.

- Ken the Car Guy


Is A/C Harder On My Engine?


I’ve heard from several people that running the air conditioning is bad for the engine.  Is this true?  Why would it hurt the engine?

-Jeff D., NV


This bit of misinformation has been around for years.  In reality, running the A/C shouldn’t have any effect on your engine.  Your engine has to run anyway while you’re driving, it might as well use some of the power it creates to make your air conditioning work.

Cars are definitely built with A/C in mind, especially nowadays.  If cars were really damaged by running the A/C, there’d be a lot more cars in the junkyard.

- Ken the Car Guy


Why Is My AC Irregular?


Recently, my AC has started acting up.  When I first start the car, it will blow cold air, but after about 15 minutes, it blows hot air.  Another 15 minutes and it blows cold air again and keeps cycling like that.  What is happening and how do I fix it?

- Horace F., AZ


The symptoms you are describing make me think that your AC unit is actually freezing itself.  As the compressor starts working, it gets colder and colder until any moisture on the unit freezes.  After seizing up, your air runs hot again until the unit thaws, after which the compressor freezes itself again.

The root cause of this problem could be any number of things, so here are a couple things you should try.

1.  If the humidity in the air is high enough, condensation might form in and on the compressor when it starts.  Try running the engine for 15-20 minutes before firing up the AC.  This should equalize the temperature under the hood and minimize condensation.

2.  Your system may be plugged.  Try removing and refilling all of the coolant.  This may free things up.

There is also a remote possibility that your compressor is actually faulty.  Unfortunately, it may need to be replaced if the above methods don’t solve the problem.

- Ken the Car Guy


What’s Leaking On My Passenger Seat Floor?


For the past few months there has been a wet spot on the passenger floor.  It seems to be worse when the air conditioning is on.  What’s happening and how can I fix it?

- Ross J., CA


On many cars, the air conditioner is located right in front of the passenger seat.  If the AC drain pipe gets clogged or dislodged, that might cause the dripping you’re noticing.

As for fixing the problem, you’re probably going to need to get under the car if you can.  Locate the drain pipe and inspect it for any cracks.  If everything seems in order, you’ve probably just got some debris stuck in the drain pipe.  To clean this out I would suggest getting a wire or pipe cleaner and prodding around in the AC drain until you can remove the obstruction.

If all goes well, the drain pipe will drip on the road instead of into your interior.

- Ken the Car Guy


Why Won’t My AC Work?


I was having AC problems, so I refilled the freon in my car’s compressor.  Now I can get cold air when the car is idling, but when I take it on the highway, the compressor seems to give out and starts pumping out hot air.  What can I do?

- Bryan P., FL


Several things may be causing your compressor to fail.  The worst possibility is that your compressor is faulty and will need to be replaced, but there’s something we can try first.

From your description, it seems like the compressor is only failing when your engine is running at high rpms.  Most compressors tend to shut down if the pressure gets too high, which can happen if the freon is overfilled.

Before replacing your whole compressor, try taking out some of the freon and see if that helps.  If you still have problems, I’m afraid you may be looking at replacement compressors in the near future.

- Ken the Car Guy


How Do I Disconnect My Compressor?


I took my car to the mechanic because it runs terribly with the AC on, and even with it off it doesn’t run very well.  The mechanic says I need a new compressor which will cost more than I paid for my car.  I don’t really need to have air conditioning, so this seems like overkill.  Is there anything I can do myself to disconnect the compressor and make the car run better?

- Davis K., CO

There sure is!  If you’d rather run your car without air conditioning, all you need to do is disconnect the belt that powers the compressor.  If you’re not familiar with your engine, the biggest problem will be finding the right belt.

Your car should have 3 visible belts, so make sure you don’t disconnect the alternator or timing belt on accident!  Once you’re convinced you’ve found the right belt, just cut it off with a sharp knife or saw.  No disassembly required.  Your car should run fine, and if you decide to add a new compressor in the future, you can replace the belt at that time…

- Ken the Car Guy


What is This Apparently A/C-Originated Hissing Sound?

Dear Ken, I bought a used 1996 Mitsubishi Galant on Cars for a Grand a while back, and just recently got it back from having the transmission replaced.

The car seems to be running fine, but I hear a low humming noise every now and then.

It happens when the air is on and it continues to make the noise after I turn the A/C off and after I turn the car off.

I was told it might be the air compressor… but I am not sure.

Any ideas?

- Huey T., NJ

Dear Huey, high pressures build up in the A/C lines while operating. The pressure builds when the coolant is being compressed.

If the A/C is cooling well, it probably is not leaking while running. If it were leaking during operation, it would soon not provide cold air.

If it makes the hissing sound for only a minute or so after being turned off, it is likely that the A/C system is simply normalizing.

Hope this helps.

- Ken the Car Guy


Why is There No Air Blowing from Any Vents?

Dear Ken, when I try to turn on the A/C, both heat and just plain old air from the outside, absolutely no air comes through the vents inside the car. Also, no air comes out the defroster vents either.

Thanks so much for your help!

- Susan O., GA

Dear Susan, when you turn the system on do you hear the electric fan spinning? If not, then check for a broken electric circuit to the fan.

This could be a fuse or a connection that has corroded or fallen loose. Check the connectors from the fuse box to the motor housing.

If you do hear the electric fan spinning, then the problem may be that a duct door which deflects the air is stuck in a closed position.

This may be caused by a failed actuator. The actuator may be vacuum activated. Check for loose or leaking vacuum lines from the manifold to the heater-A/C ducting. Also check for loose or disconnected vacuum lines from the unit control head — the part you use to control the heater-A/C system on the dash area.

Hope this helps.

- Ken the Car Guy


Why Does the Car Stall When I Turn on the A/C?

Dear Ken, the used car I just bought on Cars for a Grand has been acting weird lately. Whenever I turn on the A/C it starts jerking and sometimes it even stalls.

What do you think’s worng?

- Suzy O., CT

Dear Suzie, now your A/C takes a relatively small amount of power from the engine to run its compressor. That amount of power is a drag that pulls down the engine’s RPM just enough to cause it to stall, or nearly stall.

The engine idle decreases and it is not being given enough gas/air mixture to operate at this lowered RPM.

So the solution is to adjust the engine’s gas/air mixture to compensate for the power it must use to drive the A/C compressor.

Hope this helps.

- Ken the Car Guy


Why Does My Heater & A/C Only Blow from the Defroster Vents?

Dear Ken, the heater and A/C on the car I just found on Used Cars for a Grand both work, but they only come out of the defroster vents on top of the dash.

Moving the switch makes no difference.

Could a vacuum hose be off?

I don’t know where to begin.

- Alex R.., OH

Dear Alex, the internal doors that serve as valves to control the cold and hot air flow are not being activated. They are stuck in the defrost-mode position and aren’t able to to move in order to close and open the lower doors leading to the regular A/C and heater ducts.

First find out whether your vehicle has vacuum-activated doors or electrically-activated doors by looking at the control head.

If electric, check fuses and for loose electrical sockets and wires.

If vacuum, check for one or more leaking or disconnected vacuum lines. These sometimes come loose from the control head.

Start checking for these conditions at the control head.

Hope this helps.

- Ken the Car Guy