Automotive Air Conditioning Information Forum (Archives)

chuckwp on Wed June 22, 2011 8:31 AM

Year: 1992
Make: Honda
Model: Civic
Refrigerant Type: R134
Ambient Temp: 98
Pressure Low: 28
Pressure High: 400
Country of Origin: United States

Hello, new to forum. I have a problem child car I am trying to repair. 92 Civic. This vehicle has been worked on by others in the past. Came in with leaking compressor. Converted to R134. Flushed, changed drier,expansion valve, evaporator(was clogged externally), and compressor. Low side is normal. Highside 400+ Examination of condenser did not reveal any restriction internally, or externally.Pulled a deep vacuum for 45 min. With 21 oz. of R-134 in the sysetm: no cooling in vehicle,low side normal, high side way too high. The compressor is obviously compressing. Blend door is working properly, as heater controll valve. Have replaced expansion valve twice, thinking that was the issue. Compressor is an aftermarket reman, could it be the issue? Have never had so much dificulty repairing a system. Any advice would be helpful.

HVACNY on Wed June 22, 2011 9:04 AM

You need to upgrade the condensor to a bigger one,common issue on conversions..

mk378 on Wed June 22, 2011 9:24 AM

Condenser fan not working, too much oil, reisdual flush solvent, air in the lines?

For sure, nothing's wrong with the compressor. You don't get 400 psi from a dud unit. Getting back to too much oil, did it come with oil in it? What kind and how much?

I haven't seen one but I think the condenser is the exact same parallel flow unit used on the '94 and '95 models built for 134a. If the fins are all munched up and clogged from road debris it isn't going to work very well.

Edited: Wed June 22, 2011 at 9:25 AM by mk378

Rick-l on Wed June 22, 2011 12:19 PM

What is the temperature of the low pressure line?


(You said no cooling)

Edited: Wed June 22, 2011 at 12:22 PM by Rick-l

bromodragonfly on Wed June 22, 2011 5:19 PM

No cooling = No liquid boiling in the evaporator. If the metering device is good (I assume it is, since you've changed it twice), I would assume that there is no liquid refrigerant being condensed in the condenser, or it is not making it to the TXV.

High side pressure seems too high, and low side pressure seems too low, especially if the system has the correct charge.

You do however have a high ambient temp, so as MK said, ensure your condenser has proper airflow.

My guess is that the condenser has a restriction. When I clean them out, I disconnect the lines and take a cylinder of nitrogen and blast it into the top, from the bottom, and then from the top again. What are your static pressures at ambient, and when the compressor cycles, how long does it take the high side to rise to 400psi, and the low side to suck down to 28psi?

I retrofitted my car to R134A, keeping all the factory components (Except for new orifice, new accumulator/drier). Although the condenser won't work as well with R134A as it did for R12, it will produce liquid, and the system does get cold. I've sat in a traffic jam with around 85 ambient and a hot engine, and still had vent temps in the forties. However, I changed back to R12 last year, just because. Anyway, I would not jump to purchase and install a higher efficiency condenser when the system isn't cooling at all. There is probably something else that is wrong.


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There is no knowledge that is not power

TRB on Wed June 22, 2011 7:02 PM

Careful with these high pressures. This compressor is known to blow a hole in the side of the compressor if the PSI gets to high. Not a good conversion vehicle IMO.

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chuckwp on Wed June 22, 2011 8:13 PM

Thanks for the replies.Yes 400 psi in the high side does indicate the compressor is compressing. Condenser is not clogged or restricted. Took it off to check, Condenser fan operating. Fins not smashed, or packed full of crap. Seems like lots of hot air being pulled through condenser. Correct type and amount of oil for system Since compressor is an R12 unit, mineral oil was removed and synthetic oil was added. Don't remember the exact amount, but was around 3-4 oz. using BG Fridge Quiet synthetic type. System refergerant charge with R134 is about 85% of that recommended for R12. The high side pressure does not go way up until engine rpm is increased. I do not continue to try and operate it with that high pressure, as soon as it jumps up, I bring down the rpms, or turn it off. I did not measure the temp of the suction line, just noted that it was cold to the touch. With evaporator housing out of car could see blend door opening and closing. Recirculate/fresh air door operating correctly. Moving tem control lever to hot produces hot air out of the vents. Replaced all the rotten foam around the evaporator housing inlet and outlet for a good seal. I have done several conversions on R12 systems in the past with great success. I think this car is possesed. It should be working not putting out 70 degrees and kicking up high side pressure to 400+ psi. I know I should have refused to work on the POS. I may just have to eat this repair and that stuff tastes really awful.

bromodragonfly on Wed June 22, 2011 8:42 PM

What does the low side do when you increase the rpms?

Try taking temperatures at condenser inlet/outlet, compare to the sat temp to see if the condenser is even managing to produce liquid.

See if the cooling inside the car improves when running cold water over the condenser?

It still sounds like some kind of blockage/restriction somewhere in the high side to create a pressure of 400psi.

Is there any sign of premature flashing before the TXV? Or if you are able to go around the lines inch by inch with your hands, can you feel any odd temperature differences?

Is the receiver/drier directional, and installed properly? Are you sure you have the right TXV? And if so, does heating the TXV bulb to force it wide open make a difference?

:S I feel your pain

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There is no knowledge that is not power

chuckwp on Thu June 23, 2011 8:22 AM

Quote
Originally posted by: bromodragonfly
What does the low side do when you increase the rpms?

Goes to about 25PSI.

Try taking temperatures at condenser inlet/outlet, compare to the sat temp to see if the condenser is even managing to produce liquid.

Ok, I'll try that.

See if the cooling inside the car improves when running cold water over the condenser?

High side went down a little with a big ass fan blowing at condenser, but cooling did not improve.

It still sounds like some kind of blockage/restriction somewhere in the high side to create a pressure of 400psi.

I know, I thought this might be the case. All high side lines were unbostructed, proven by blowing air through them. Reciever/drier not clogged. No crud visible in TXV.

Is there any sign of premature flashing before the TXV? Or if you are able to go around the lines inch by inch with your hands, can you feel any odd temperature differences?

Can't get to every inch of the lines, but generaaly the low side was cold and the high side hot.

Is the receiver/drier directional, and installed properly? Are you sure you have the right TXV? And if so, does heating the TXV bulb to force it wide open make a difference?

TXV and drier OE parts from Honda. The first TXV was afetrmarket, I didn't trust it. It had extra long lines to the bulb and equalizer tube that I had to coil up and cram into the evap. case. Of course, changing it to OE didn't make any difference.
Receiver/drier can only go one way.
No way to get to TXV bulb as it is inside evap. case.
So, now can you see my frustration. Nothing makes sense, it should be working. I have about $600 in parts (my cost) in parts in this thing, and way too much time. I gave the car back to the guy for now. I have other work to do, and just need not to even look at the damn thing for a few days. I am hoping the light bulb will go off above my head and give me the answer before I get the car back.
:S I feel your pain



Edited: Thu June 23, 2011 at 8:30 AM by chuckwp

bohica2xo on Thu June 23, 2011 12:39 PM

Well Chuck, at least you now know when the bad advice fairy whispers the words "134a conversion" & "Honda" in the same sentence - you should throw a hammer at him.

Condensors on those cars are just not up to 134a & high ambient temps. A brand new condensor with no blocked paths will do ok, but expect to see 300 psi with 100f ambient temps.

B.

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