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'94 Honda Prelude a/c comes and goes

engatwork on Sun August 03, 2008 9:24 AM User is offlineView users profile

Year: 1994
Make: Honda
Model: Prelude Si
Engine Size: 2.3
Refrigerant Type: r134
Ambient Temp: 85
Pressure Low: 38
Pressure High: 155
Country of Origin: United States

This one has been kicking my butt. Purchased the car without the a/c in operation. Replaced the compressor (reman), condenser (because of all the metal that was in the oil in the compressor), dryer and expansion valve. When I disassembled it I found some little balls in the system so I blew everything out real good. Buttoned everything up and started it up and it did not work as it should. Tore into it again and took evap out and found the discharge line plugged up with these little balls in addition the expansion valve. Replaced the expansion valve, blew out the discharge line between the dryer and the evap and put it all back together. Ran it a day and same thing. This time I removed the dryer, exp valve and evaporator. There were still some more balls in the system. This time I blew the evap out, cleaned out the exp valve (more on this in a minute), blew out the discharge line between the dryer and evaporator and put it all back together. At idle the a/c seems to work as it should and I obtained the pressure readings at idle. Seems to work fine up to around 3k rpm after which time the cold goes away. I don't think the compressor is dropping out because it does not drop out when I rev it and the car is stationary. The low side approaches 0 psi when I bring the revs up. At one time yesterday I was getting clouds blowing out of the vents. My plans are to watch this post throughout the day and tear into it again this afternoon to see if all my balls are gone. I'm thinking I may still have some. Man, this thing has been kicking my butt. Thankfully it is a Honda and not a Mercedes I'm having to pull the evaporator out of.

oh, one more thing
I unscrewed the allen fitting out of the expansion valve to clean it out. This allen fitting presses against a spring and at the top of the spring is a dished disk that the expansion valve needle stops against. How critical is it that I got the correct amount of tension against the needle. Unfortunately, I did not count the turns as I disassembled it.
tia

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Mechanical Engineer in a paper mill.

Edited: Sun August 03, 2008 at 9:32 AM by engatwork

HECAT on Sun August 03, 2008 10:03 AM User is offline

The oils will bind the "little balls" (dessicant, sealer, debris, etc. ?) in the corners, crevices, and common chambers of the complex paths within the heat exchangers; as soon as the air (blew out real good) finds it's way through, no more of this junk is going to blow out. This will continue to leave the debris and oils in there when you button up and finish (vacuum, oil charge, refrigerant charge). You probably still have more of this junk and excessive oil in the system and a proper liquid flush to achieve a "Clean & DRY" starting point is required. Then you can add the proper amount of fresh oil and recharge. This system holds a very small quantity of oil and refrigerant and needs to be clean and right to perform properly. See the proceedures page for more details about sucessful and proper flushing principles.

Cannot answer the specifics of the TXV reasembly, they are usually blown clear without dissasembly if attempting to reuse; I personally would replace it. It's not a Mercedes, but it is still a PIA to go back in again and again.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

mk378 on Sun August 03, 2008 11:42 AM User is offline

That allen screw sets the pressure / temperature characteristics of the valve, it is calibrated at the factory and shouldn't be touched in the field. You would have to tinker with it a lot to get adjusted again, much easier to set that valve aside and buy a new one instead.

But you have to get all the little balls out first, that could mean replacing the entire system again.

engatwork on Sun August 03, 2008 6:09 PM User is offlineView users profile

ya'll were right. I had some more little balls in the system. Looks like this time there were alot less than the last time. Hopefully, I am getting close to getting them all out. If it is not much better then I am going to replace the evaporator and maybe the discharge line between the evap and dryer. I cleaned the balls out of the 1st new expansion valve I had purchased and put it back in.

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Mechanical Engineer in a paper mill.

engatwork on Sun August 03, 2008 8:58 PM User is offlineView users profile

Went for a test drive on the interstate and it quits blowing cold above about 70 mph now. My plans are to install a new evap and blow it out again.

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Mechanical Engineer in a paper mill.

mk378 on Sun August 03, 2008 10:18 PM User is offline

I suspect a bunch of those little balls are lodged in the condenser, and without a powerful flushing machine the only way to fully be rid of them is to replace the condenser. Also take the compressor off the car and work a lot of oil thru it to clear any out of there. If there are any left anywhere it will be for nought to replace the evaporator, they'll just get in it again.

engatwork on Mon August 04, 2008 8:46 PM User is offlineView users profile

The condenser was installed new when I replaced the compressor and all this started. I picked up an evaporator this afternoon and will be installing it this weekend. I suspect the existing evap has some balls stuck in it too. I went through the system from the condener through the evap this weekend two different times and when I blew the condenser out I did not see any indication that there were any balls in it. I suspect the existing/original evaporator is pretty plugged up. A/C works great from idle up to around 70 mph.

I'll keep ya'll posted. I'm kicking around the thought of purchasing one of those pulsating flush systems to start using. If I work on many more Hondas I will pick one up.

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Mechanical Engineer in a paper mill.

engatwork on Sun August 17, 2008 8:30 PM User is offlineView users profile

Still don't have it sorted out.

I went through it again today. Disassembled everything, blew everything out drained the compressor, poured new oil in, drained it again and did it a few times. I blew through the condenser, inspected the expansion valve and flushed/blew through the evaporator. Added the correct amount of oil, buttone everything up, ran a vacuum, recharged and tested it out. Now with it slightly undercharged I am getting around 25 psi low side and 300 psi high side (when I jump the compressor) at idle and an ambient temp of around 85dF. It lifted the compressor relief valve yesterday when I had it jumped out without the gauges on it.

I ended up having to replace the line going from the dryer to the evaporator. I suspect I have plugged the new condenser.

In addition to all this now the light on the dash that indicates power going to the compressor is not coming on. I'm probably going to throw in the towel and take it to the Honda dealer.

Here are the parts used so far:
Compressor (2) - the first one would not make any pressure.
Condenser, evap, exp valve (2), dryer (2) and the line from the dryer to the evaporator.

This has been the most difficult a/c I have ever tried to make work and will use this experience when purchasing another used Honda.

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Mechanical Engineer in a paper mill.

Edited: Sun August 17, 2008 at 8:32 PM by engatwork

engatwork on Mon August 25, 2008 6:45 PM User is offlineView users profile

Finally got it sorted out. The dealer was absolutely no help but on the same hand there was no charge. I ended up having to replace the condeneser and dryer again. I have learned a lesson on these Hondas. If you come accross one that the dryer has gone bad on you need to just go ahead and replace EVERY component. It will save a bunch of grief. I also found a burned out solder joint on the a/c pushbutton unit.

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Mechanical Engineer in a paper mill.

HECAT on Tue August 26, 2008 9:39 AM User is offline

Quote
Originally posted by: engatwork
I have learned a lesson on these Hondas. If you come accross one that the dryer has gone bad on you need to just go ahead and replace EVERY component. It will save a bunch of grief.

Flushing works very well too.

Flush or replace. Either way, it's got to be clean and DRY before you can button it up. Anything left in the system will also migrate with the refrigerant and oils until it finds a place to rest; in many cases causing continued performance related problems and repeat failures.



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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

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