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Air Conditioning Performance.; What do we expect?
Topic Started: Sep 4 2017, 10:20 PM (663 Views)
coreyare
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I recently equipped my 91 Geo, with ac using parts off a wreck.

Being stubborn, and not wanting to do the r134a conversion process, We've experimented using r290 (Hank Hill juice), and the results are less than flattering, I tell ya 'hwhat.




The compressor is a little on the noisy side, this is possibly due to the higher head pressures pushing those larger gas molecules...,

more over, on an 80 degree day (summer time in Seattle), the performance, is a tad lack luster....




Sitting in the shade with the engine idling at 1000 ripums, fans full blast, recirc, the air coming from the vents is not very cold at all, despite having high side pressure teetering on the edge of tripping the two-way pressure switch. We've tried adding more, and removing refrigerant, but no bueno...

AC does decent, cruising at 2500 rpm....though my gas gauge gets a little E-ccentric






So here's a few questions:



Should I consider using a mixture of propane and butane refrigerants? (those frosty the snowman substitute r12/r134 can things you see on fleabay)




Is this all a Geo Metro can do when using AC?





and/OR





Should I just throw in the towel and convert it to r134a instead of risking singing my face fur when a leak decides to ignite? (are the r12 neoprene seals compatible with the pag oil?)

I believe I have a spare can of that ebay stuff laying around somewhere....
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Stiffchezze
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Sir Metrologist

Alot of ambiguous information here...

To help diagnose, we need a bit more information. Any chance you can get us actual vent temps as well as outside temps? Pressure numbers too. A meat thermometer works well to get vent temps.

To put a Metro system in perspective, down here in the deep south, when we say at 100% humidity it's "starting" to get a little humid, :whistle with a outside temperature in the 90's I've gotten many a Metro R-134a A/C to give me 50's or less out of the vents. And when the heat backs off a tad, I've gotten 30's. Of course this is a properly rebuilt, flushed and filled system.

It is possible to get pretty good A/C out of a Metro, but there are no shortcuts. I don't have alot of experience with the R-12 substitutes, but I'm sure some of the folks on here have.
Be happy to help any way I can. :thumb
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JellyBeanDriver


You say your high side is high, but what's your low side? That's the evap temperature. High high side just means the high side is HOT and you're not pulling the heat out of it from the condenser.

R134A won't perform well in a system set up for R12. I had dealer installed AC in my '92 which never worked well. Tried the HC fill off ebay - didn't work well. Tried R134A, didn't work well. Ended up putting in the AC system off a 97' (R134A) and now the AC is great. Have to swap the engine crank pulley to a 95 (I think) to get the smaller diameter, which you also end up with a 5 bolt pulley so the cam gears and belt need to change too. It's not too bad to do but it's not easy either.
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CMA


Did your dealership actually FULLY retrofit it to R134a from R12?


Something is really wrong.
Edited by CMA, Sep 5 2017, 01:05 AM.
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Woodie
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None of them work very well with the car sitting still. Gotta get some airflow through that condenser.
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clen
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Buy 'Em Up! Now!

I have a 2001 and I have fans on my condenser and it's still lackluster in performance.

I took it in to get it looked at, they recharged the system and checked for leaks.

I think the A/C system is just meh. it keeps the cabin warm and not really hot. I'm better off opening the windows.

I would upgrade it but I don't know where to start.
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coreyare
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Stiffchezze
Sep 4 2017, 10:41 PM
Alot of ambiguous information here...

To help diagnose, we need a bit more information. Any chance you can get us actual vent temps as well as outside temps? Pressure numbers too. A meat thermometer works well to get vent temps.

To put a Metro system in perspective, down here in the deep south, when we say at 100% humidity it's "starting" to get a little humid, :whistle with a outside temperature in the 90's I've gotten many a Metro R-134a A/C to give me 50's or less out of the vents. And when the heat backs off a tad, I've gotten 30's. Of course this is a properly rebuilt, flushed and filled system.

It is possible to get pretty good A/C out of a Metro, but there are no shortcuts. I don't have alot of experience with the R-12 substitutes, but I'm sure some of the folks on here have.
Be happy to help any way I can. :thumb
We're running 30 PSI on the suction side, and about 300 on the high side.

Vent temps on an 80 degree day with about 50% humidity are about a 15-20 degree delta, sitting in a concrete driveway running about 1000rpm

performance picks up to about a 30 degree delta when traveling at about 2500 rpm in third gear, or 2500rpm in 5th gear on the freeway.



The system is bone stock with the original black rubber seals, it was pulled off a wreck in a wrecking yard and did not seem to have much refrigerant in it.

*side question* If I were to convert it to 134a, would I have to change all the seals out, in addition to flushing the mineral oil out?

Quote:
 
Did your dealership actually FULLY retrofit it to R134a from R12?


Something is really wrong.


Nope mine was not equipped when I bought it, I equipped it with parts I pulled off a 91 wreck.



Thanks for coming to aid everyone!
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David95237


I have R12 if you want any.
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Mrbreeze


You know, I converted the 93 over to r134 several years ago, a couple weeks after that the a/c stopped working, recharged it and it was leaking out as fast as I was putting it in, the o-rings had dissolved, replaced them with compatible ones and it worked awesome for years, this year coming back from flagstaff it stopped working, got it home and discovered that the clutch bearing was toast, I replaced the compressor with a new one from AZ and I'am very disappointed with performance, I've played with the pressures, evacuated and recharged, I haven't figured it out yet, just thought I'd share..
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bkgeig
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Don't know whether this will help you, but when I installed a junkyard system on mine I called around until I found a place that still does R12. It's a bit more expensive, but for our small systems not much. The difference between R134a and R12 isn't drastic I think, but every small bit helps in our systems. My next step is to tint the windows.
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MarkZ28


Butane and propane should work ok. Anydrous ammonia also works but is very very corrosive to humans, lol.
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nwgeo


I converted my 94 over to 134 with used junk.... ice cold... much better though when moving. Lost the compressor aftera couple of years and put another used on in.... ice cold... used to the wal mart converstion kit.

I now have a converted 98. Again used the same conversion kit lines I bought for my 94, worked great. Going down the road with my 98 3/5 it will blow you out, even on a 100F day I have to turn it off every so often or it will freeze me out.
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David95237


I thought a 94 already had 134 in it. 93 was the change over year. And why would you have to change a 98?
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geogonfa
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Okay...Just my .02¢

Let me see if I can add to the confusion...

Your posted pressures at idle show the expansion valve is not working right...and/or possible over fill...
you should have replaced the "O" rings that have already been used in the original system, and you didn't mention replacing the receiver/drier, as well as pulling a proper vacuum...

as for further info go to:
http://geometroforum.com/topic/8111407/5/#new
post #67


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coreyare
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geogonfa
Sep 5 2017, 06:12 PM
Okay...Just my .02¢

Let me see if I can add to the confusion...

Your posted pressures at idle show the expansion valve is not working right...and/or possible over fill...
you should have replaced the "O" rings that have already been used in the original system, and you didn't mention replacing the receiver/drier, as well as pulling a proper vacuum...

as for further info go to:
http://geometroforum.com/topic/8111407/5/#new
post #67


Thanks for your post, it certainly helps clear up a lot of ???'s lol

We did do the proper methods of pulling a vacuum on the system and replacing the reciever dryer. We didn't consider replacing the expansion valve, but now that you mention it, we may just have to throw in the towel, and tear into it again >:O The foam on the blower motor casing needs replacing anyway D: discovered that after cleaning a dead mouse out of the blower wheel....


Since we're still using the mineral oil, we decided to keep the original neoprene seals, as we were using r290(propane) instead of retrofitting it to r134a, only seems to be a mild leak from the sight glass :( , and a little bit on the compressor adapter plate :(

Kicking self in rear realizing the unholy process of R&R of all those seals when it comes time to do it all over again. :banghead


Its a learning process all its own, and my god is AC work DIY unfriendly :(



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