Automotive Air Conditioning Information Forum (Archives)

amphicar770 on Mon May 09, 2011 10:13 AM

Year: 1995
Make: Alfa
Model: 164LS
Engine Size: V6 24V
Refrigerant Type: R134
Ambient Temp: 78
Pressure Low: 65
Pressure High: 200
Country of Origin: Italy

Hi All,

I have a '95 Alfa 164LS. A/C was not cool.

Took it to shop where they diagnosed leak at expansion valve and expansion valve not working. Some $600 later they replaced the valve, recharged system, put in some UV dye. (person I bought car from paid for that work).

A week later and A/C not blowing cold as it should. I hooked up gauges and get the following:

Outside temp is about 79 degrees.

LOW HI
100 100 (with engine off)
60 175
65 200
70 225 (about when fan kicks on)
60 175 (fan goes off)
67 225 (fan on)

Temp from center vent probably a low of about 60 to a high of around 70.

As I probed around further I notice some dye at edge of the condensor. Confirmed this using UV light.

Could the too high readings on the low side be caused by the condensor leak or does it sound like I am also going to get stuck replacing the compressor? Any suggestions on further testing before I start randomely replacing expensive parts?

Thanks,

Mike





Edited: Mon May 09, 2011 at 10:14 AM by amphicar770

bohica2xo on Tue May 10, 2011 1:30 PM

Does not appear to be anything wrong with the compressor - it manages to push 200+ psi. Unless it makes some evil noise or is slinging oil & dye, leave it alone.

The condensor leak may be a fitting - or is it a long way from the fittings?

The relatively steady 60 psi on the low side looks more like an expansion valve issue to me.

B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

pippo on Tue May 10, 2011 11:08 PM

I was not aware that low side psi could go to 60 and 70 safely and be normal and functional. I always "heard" 30-40 was more typical psi's........what is going on?

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beware of the arrival

mk378 on Tue May 10, 2011 11:28 PM

Is it a variable displacement compressor? Those systems must be known to be properly charged before starting to diagnose.

Amphicar on Sat May 28, 2011 12:20 PM

Thanks for the feedback. This one has me stumped. Here is the update. Hope someone can help.

1) As noted, shop flushed system. replaced expansion valve. and recharged including some UV dye.

2) In July 2010 the dealer had replaced the the expansion valve, poa valve, and dehydrator.

2) A/C was not especially cool. I notice low side reading at around 70. As pippo noted, 30 should be about normal.

3) I notice UV dye at both sides of condensor near bottom and also a slight dye / oil drip.

4) Today I replaced condensor and receiver/drier. Added 1 0z oil to receiver, vacuumed down system, recharged with specified 42 oz R134 using a refrigerant scale. I did not replace expansion valve as that is one month old. Figured life would now be good.

5) Low side readings around 70, high side around 225 Vent temps around 68 degrees.

It is a Sanden compressor, nothing too exotic other than the pulley. Woul a compressor go bad on the low side?? Any theories or ideas welcome.

Thanks,

Mike

ice-n-tropics on Sat May 28, 2011 3:20 PM

LBJ had a Amphicar on his ranch (the Texas White house) in Texas and would scare guests by driving into the Perdenales river when not sober.
1) Abnormally high suction pressure is not:
Compressor because discharge pressure is normal. To further prove this you could place cardboard over the condenser until the discharge climbs to 350 psi.
Leak from anywhere because a leak always results in too low suction pressure
2) Possible causes:
Non condensables (air) inside refrigerant circuit
Blocked circuit inside evaporator coil
Evaporator fins loose from tube contact or corroded away
Evaporator coil with internal by-pass due to faulty manufacture or over pressurization during service
Expansion valve blocked open mechanically or not closing due to bad contact with capillary tube bulb against suction tube. Causes frost/ice on suction line.
POA valve (don't think Alfa used in 1995) not modulating toward closed position
Too much oil in system will give warmer temps than indicated by the pressure
Cordially,
hotrodac

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Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

Edited: Sun May 29, 2011 at 3:44 PM by ice-n-tropics

amphicar770 on Mon May 30, 2011 7:50 PM

Yes, i have a photo of LBJ on the ranch on his Amphicar!

Poa valve replaced last year by dealer. Expansion valve replaced last month. Condenser and drier this weekend.

Any advice on where to start. Should I first try having the evaporator flushed if I can find a shop with a Hecat or similar equipment. Should I start somewhere else first, even for diagnosis?

Thanks.

Mike

Amphicar on Fri June 10, 2011 3:51 PM

Hi All,

The nightmare gets weirder, with more $$$ down the drain.

The Alfa does use a POA valve. After reading that this could cause hi readings on low side, I swapped it with one from same year parts car. After doing so, I coul dnot get it to take more than 1.05 lbs. I then brought it to ALfa shop for some other work and asked them to check it out.

They added additional R134 and reported back that it was freezing up. They evacuated system and put back the POA valve that I removed (which, upon inspection, most certainly looks like it too was a used unit. New oness are unobtanium).

After they charged the system back up it still blows a max of just over 60 degrees. As they described it, the system is improperly cycling. I got home, hooked the gauges back up. Now, instead of a steady low reading of 70 psi, what it is doing is that it floats up to 70, drops down to about 30, floats back up to 70, repeat. Hi side remains relatively steady at around 275ish.

Any ideas greatly appreciated. At this point I have $500 at first shop, I replaced condensor and rcvr drier on my own, another $300 at 2nd shop. Not fun.

Thanks,

Mike


Edited: Fri June 10, 2011 at 4:44 PM by Amphicar

mk378 on Fri June 10, 2011 5:06 PM

You should rig something to bench test the POA valve with air, as is well known for the old GM ones. Supply compressed air to the evaporator end port and leave the compressor end open. The valve should regulate the pressure at the inlet (evaporator) side to about 25-30 psi regardless of the flow rate.

Compressor should not cycle on and off on a POA system-- it should run constant as long as the A/C button is pressed. The low side is regulated by the POA valve. Air in the lines (neglecting to evacuate) can cause freeze-up.

Amphicar on Fri June 10, 2011 5:34 PM

I just hooked the removed POA valve up to my compressor. Fit perfect on the black pipe I run air through!

Anyway, what I observe is that at lower pressures it does let some air pass and then at approx 32 psi there is a definite pop and it opens full. Does this sound correct? It is an R134A system.

Is it possible that I got a bad expansion valve even though it is new?

Thanks.

amphicar770 on Tue June 14, 2011 7:32 PM

Looks like I found the problem.

There is a small copper tube from the expansion valve. It has a fitting on the end that screws into a similar line from the poa valve.

Looks like shop who did the x valve must have bodged the fitting on the line. They thus snipped off the fittings and put a solder joint between the two lines. This in turn blocked the line completely at that spot.

Now I need to hunt down a replacement line.

amphicar770 on Sat June 25, 2011 3:09 PM

Hi all,

Aft replacing the expansion valve and using correct pipe, my crazy jumping pressures have gone away. I was still not getting sufficient cooling and just tried swapping poa valve with one from parts car but no change.

Hi pressure at idle is about 250ish. When I bring rpm up to 1500 it goes to about 300. Low is around 40. Ambient temp is 85 degrees. Vent temp at idle (with air blowing over condenser) is only around 60. At speed I might get to around vent temp of 50. System is charged, using scale with 2.4 lbs.

Do these pressures seem right? I am wondering if with all the shops that worked on it if there could be too much oil in the system? Any other ideas welcome. This is really frustrating!

Thanks.