Still having A/C issues please help

[2-Saw]

First off I want to say thank you to BRIANK for looking at my CCU twice, and all the help he has given me. He is an invaluable member of prime, and if anyone has board issues, he is the guy. Also, Larry thanks for your help trying to figure this out. My indash temperature sensor is working perfect now that the hairball is out of it. Now for the problem:
I have been having A/C issues in my 91 since August 05. The problems are:
1. The system seems to work perfect fo about 20 min, then the fan starts to slow down. It works on all different speeds, just slow to trickle.
2. While it is going down, the air only wants to be cold on 60, and hot on 90.
3. Then out of no where after about 1 hour of driving, it all comes back working perfect, and it starts over again.
I have sent board for repair 2 times, not the board. Inboard sensor works, now. I have ran the self diagnosis, both of them and nothing. Although, come to think of it, I haver not rean the diag when the problem occurs. Probably too busy cussing. I have read the Acura service bulletin on the 91-92 years, and its symptoms are it only runs on high speed affecting the blower motor and power transistor. I am completely out of ideas, any help given will be gladly taken. Ijust hope it can be fixed with out Acura salivating for the $4000.00 to replace the system.:frown:
Dean

 

[Zennsx]

For starters I would definately replace the power transistor, Sure transistors are more inclined to fail catastrophically, ie (collector to emitter short) resulting in high fan speed only, but from the symtom your describing (fan working for 20 minutes then slowing to a trickle speed) leads me to believe its a transistor with a thermal or current (Hfe) problem . Hope this helps

 

[53heloFE]

I have ran the self diagnosis, both of them and nothing. Although, come to think of it, I haver not rean the diag when the problem occurs. Probably too busy cussing.

That's the problem, she doesn't like being cussed at :biggrin: I would be curious to know how the tests turn out if you ran them as soon as it started acting up. After being an aircraft mechanic for many years I can understand how hard it can be to try and fix a problem that is not constant.

I am having A/C issues too, and BRIANK has been a great help. It is awsome to have such help from others in our community. My A/C will not kick in using the CCU but every test in the book works fine, and I have run them more than once, replaced a fan control unit and a new CCU board. My whole CCU will be on its way to BRAINK on Monday to let him troubleshoot that part of the system.

 

[2-Saw]

I pulled the blower motor, and found soo much crap in the motor. There was alot, I mean alot, of a black powder, from brushes, and lint from? I also pulled the transistor, and it had crap all over it as well. 45 min and 2 toothbrushes later the motor, and transistor are clean. mabey this will help. Dont know but will keep all posted. Putting all back in tomorrow. When i mean alot there was about a total of 3/4 a shot glass full of crap on connectors and motor

 

[Zennsx]

You could also need motor brushes.

 

[Briank]

Dean (2-saw) I hope the cleaning job on the blower motor takes care of your problems.

Jason (53heloFE) I will get right on your CCU when I get it.

 

[DDozier]

You could also need motor brushes.

I think Zennsx is right, the transitor fails due to the failure of the brushes in the blower motor. When they fail the blower still spins but the current draw from arching brushes causes the transitor to fail. I think I would replace the blower now before the transitor fails and you have to replace both.

Just my .02

59912 Item# 005 1 MOTOR ASSY., BLOWER List 224.67 Disc. price 190.97

Dave

 

[Briank]

A blower motor with bad brushes will draw less current and is unlikely to cause a failure of the power transistor. A blower motor with bad bearings (tight) or shorted armature windings will draw too much current will cause a failure of the power transistor assembly but the transistor will not be the part of the assembly that fails. Inside of the assembly is thermo fuse that opens.

 

[Zennsx]

A blower motor with bad brushes could be 2-saws only problem. The transistor theory was an educated guess.

 

[2-Saw]

My new clutch came in today:biggrin: , and i only drove it for about 10 minutes to the shop. I dont know yet but fingers crossed.

 

[2-Saw]

Both brushes were a little over 1/2 inch each:smile: the total length of the brush sleeve, where the brushes are kept behind 2 springs, is exactically 1 inch. So i figure, the car being a 91, i got around 70,000 more miles, or about 28-30 years. Now after shooting my mouth off, I still dont know if the problem is solved. I do know this. I can and will help anyone with similar issues. Primarily concerning removal and cleaning of parts before buying new. Man its late. I really have OCD with this car!!

 

[2-Saw]

Blower motor runs perfectically!! :biggrin: :biggrin: If the motor is not running correct. It is really hard to diagnoss. The temp is a little off, mabey front ambient temp. Dont really care.:tongue: I can figure it out in my own time now. Does anyone know how to test the front temp sensor in the grill of the car? Thanks for all the help!!

 

[Briank]

Dean

There is a chart in the service manual that shows what resistance the sensor should be at a given temp. There is also a switch on the top of the CCU that you can use to adjust the temp. +- 1.5 degrees from the setpoint.

Brian

 

[2-Saw]

Thats right, I remember it now. How do you tell the temp of heater/ ac? Use a meat thermometer? Should you have the a/c be on, even if you are using it to check the heat temp temp? Is there a way to see if the grill sensor is working correctly?

 

[Briank]

Take a thermometer with you in the car and see how well the system is holding the set point. The grill sensor just changes the way the system controls the interior temp but not the temp. The sensor you may what to test is the one in the aspirator fan inside the car.

 

[Jett]

bump...