My first post here please forgive my inexperience. My car has had this problem for years, it first started blowing snow out of the vents and then no a/c and then no air came out of the vents even though the fan was blowing you could hear it blowing yet no air came out of the vents. I took it to the shop and they found nothing wrong and it was working fine. This went on for years. Then last year the a/c came on and wouldnt turn off. It was freezing cold in that car in Md. in the winter. Two shops suggested it was the Temp.control assem.(Computer Head) that needed to be replaced so although expensive I finally had it replaced . I only see the car twice a year when my son comes home from school and when he drove up from Ga. last week and needed to turn on the heat the fan wouldnt blow the air out into the car even though you could hear the fan was on and blowing. This time the shop said the a/c evap had literally frozen into a block of ice even though the a/c was not turned on. I understand air cant flow through a block of ice and maybe thats why I could hear the fan but couldnt feel the air come out of the vent.And once the block of ice melted the air flowed fine. My son had to leave so I unplugged the a/c compressor clutch so the a/c wouldnt turn on and got him on the road while I researched the problem. Is it possible there is a bad pressure switch not cycling the compressor off? Is there a switch that turns the a/c compressor on and off?
Hope I didnt digress to much Thank you so much for your time.

...Tiana

 

By no means am I an AC expert. If you are not getting any codes from the "atuo climate" unit. Can you test the compressor relay? A reach but is it stuck closed?

 

First, I wanted to be sure whether this is Automatic Temperature Control (ATC) or manual temperature control. You mention "computer head" implyiing ATC. IF ATC, there is a diagnostic that can be performed to determine some faults.

If ATC, on my 97 Acura TL, the codes are accessed by pressing the Auto and Off buttons at same time w/ keyswitch On. Part of ATC display will come on. Post back what you see and hopefully we can intepret.

A very likely fault is the evaporator temperature sensor. This sensor tells the ECU when temperature of evaporator is near freezing and ECU disables compressor to prevent freeze-up. If a false (too high temperature) is sensed, the compressor will run full time. Another possibility is the sensor is simply not inserted into the evaporator (pulled out accidentally perhaps). In this case, a correct false high temp would be sensed. Evap temp sensor could also be the problem w/ a manual system.

good luck

 

If it were stuck closed would that make the a/c stay on? not cycling on and off? Is that called an a/c compressor relay ? I dont have the car with me right now and might have to have someone else check it out for me. I just need to have a clue as to what to check the next time its here . This car has had all scheduled maintenance and this is the only problem she has and I really want to make it right.
Thank you so much for your help.
...Tiana

 

Yes, a failed-closed compressor relay would cause the compressor to stay engaged at all times. Hard to believe someone didn't check this w/ earlier work, but you never know.

good luck

 

You should just unplug the compressor, so you do not get the air flow problem. Ice building up over the evaporator can not be good for it.

I would definitely test the compressor relay and the connector the relay plugs into. You will need a volt meter to do this. It is a pretty simple test.

 

My mistake I think its called an a/c control module head not computer . I'm thinking its not an ATC I'm sorry. Here is the work I had done.

Shop #1 independent shop
The 2008 repair reads: The evap temp sensor replacement resolved the a/c cutting off when it was plugged in, but not when mounted into the evap. After the installation, the a/c went back to cutting off-we have no idea why.The sensor is bypassed now.
Shop #2 Certified Honda Dealer
2009 recommendation reads: inspection found electrical concern with a "open" in the wire between the #3 fuse in the drivers fuse/relay box(drivers side under the dash) and the a/c compressor clutch relay. Recommend replacing a/c control module $576.00 to begin the job with used part and cant guarantee it will resolve the problem.
Shop # 1
2010 the a/c was stuck on so I went ahead with the repair the dealership recommended in 2009 but but had the work done at the independent shop. They replaced the temp.control assembly and I cant find the receipt but it was around $400.00 with new part not used like the dealer wanted to use.

2011 a/c wouldnt turn off even though control was on heat not a/c and the a/c evap froze into a block of ice. So now I do have the a/c compressor clutch unplugged but dont want to leave it that way.

Thanks again for your time.
I dont understand all of the shop talk above maybe it will make sense to you.

...Tiana

Thank-you

 

There are two items that you can easily check right now.

1. When the engine is running with the connector to the compressor unplugged, does the clutch plate spin with the compressor pulley? On the parts diagram below, the clutch plate is between #6 and #11. The pulley is above #2.

Make sure the a/c is turned off in the car. Plug back in the connector to the compressor and see if the clutch plate starts spinning. Unplug when you are finished.

2. Do either/both radiator fans start running as soon as you turn on the engine when the engine is cold?

 

I dont have the car right now my son had to go out of town however as soon as I get the car back I will check out everything I learned here and post my results . I dont want you to think I just went missing with all the information I received here today. I appreciate the time and knowledge you shared. I will post the results so you will know how it turns out but it might be a while befor I get the car back.

Again I cant thank you enough for your time.

...Tiana

 

"Shop #1 independent shop
The 2008 repair reads: The evap temp sensor replacement resolved the a/c cutting off when it was plugged in, but not when mounted into the evap. After the installation, the a/c went back to cutting off-we have no idea why.The sensor is bypassed now."

Above suggests Shop #1 bypassed the AC Thermostat to enable the compressor. This would also cause the Compressor to run all the time the AC Switch is On. This entire problem may stem from a faulty AC Themostat.

Does the AC Panel, AC On/Off switch disable the compressor?

I think you've been the victim of some shoddy diagnosis and repair. The manual AC system is admirably simple, easy to diagnose, and repair.

good luck