Those who've done R134 conversions....
08-12-2009, 01:04 PM
#16
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Ha! I thought I did a cheap conversion, but I see I 'splurged' when I actually replaced my accumulator! 3 years now, after putting in a new compressor (rear compressor mounting lug was broken when I bought it), new accumulator, vacuumed it down, charged with oil and R134. Still blows cold.
08-12-2009, 04:56 PM
#17
Rennlist Member
Did one to my 928, and it works great. Had an issue with someone cutting the compressor wire. Figured I replaced Rec/Dryr so might as well update. Only changed the "O" ring seals. Works great no complaints. A/C is cold and functions well. Althought, I believe during the winter I may change the compressor. Saw a little wetness there. But will wait and see if I lose coldness.
08-12-2009, 05:19 PM
#18
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....
On the early 944s and 924S- it is a 1 hour job to drop the evaporator/fan without removing the dash. The later cars require hours of labor. I mention this because the PET does not list individual "O" rings for the expansion valve. It is a Porsche only 2 piece kit. ~$4.....
GL
John_AZ
On the early 944s and 924S- it is a 1 hour job to drop the evaporator/fan without removing the dash. The later cars require hours of labor. I mention this because the PET does not list individual "O" rings for the expansion valve. It is a Porsche only 2 piece kit. ~$4.....
GL
John_AZ
08-12-2009, 05:44 PM
#19
Proprietoristicly Refined
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About an hour, less if you did a second unit. Even the assembly went smooth-I just looked at the '88 
My freon leak was in the evaporator coils. Replaced with nearly new unit from EBay. You are correct about the black goo. The "O" rings on the old expansion valve fell apart.
AutoZone had a 8oz bottle of PAG. I used 5oz. A few techs said that esther may eat seals. I could not find out more so I stuck with what was on the shelf.
AutoZone also had a can of pressurized flush ~$15. For a 1 time job there is enough for a complete flush if you do not waste any. Easy to use. I did not want to experiment with "other" liquids.
WalMart had the R134a for $6.99 a can.
GL
John_AZ
1988 924S + 1987 924S
My freon leak was in the evaporator coils. Replaced with nearly new unit from EBay. You are correct about the black goo. The "O" rings on the old expansion valve fell apart.
AutoZone had a 8oz bottle of PAG. I used 5oz. A few techs said that esther may eat seals. I could not find out more so I stuck with what was on the shelf.
AutoZone also had a can of pressurized flush ~$15. For a 1 time job there is enough for a complete flush if you do not waste any. Easy to use. I did not want to experiment with "other" liquids.
WalMart had the R134a for $6.99 a can.
GL
John_AZ
1988 924S + 1987 924S
08-13-2009, 10:10 AM
#20
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Sure they do, provided your compressor can keep up. That's what I used - pulled 29" InHg for two hours regulated 90psi at the venturi pump. I'd prefer an electric pump, but I won't touch a junk Harbor Freight pump again. The one I want is over $300 and no more A/C work than I do, I just can't justify it.
08-13-2009, 11:31 AM
#21
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I converted last year when I replaced my compressor with a rebuilt one from eBay. I didn't replace any O-rings, flush the system or even replace the receiver/dryer. The only thing I did was evacuate the system for a couple of hours, verify the system could hold a vacuum for 24 hours, then recharged with R134a. Works very well except on 90°F+/90%+ humidity days. It still cools, but just not as well until after it runs for about 20 minutes.
I need to check my charge with the gauges just to be sure everything looks good, even though it's working well. I haven't touched it since fixing it last year.
I need to check my charge with the gauges just to be sure everything looks good, even though it's working well. I haven't touched it since fixing it last year.
Sure they do, provided your compressor can keep up. That's what I used - pulled 29" InHg for two hours regulated 90psi at the venturi pump. I'd prefer an electric pump, but I won't touch a junk Harbor Freight pump again. The one I want is over $300 and no more A/C work than I do, I just can't justify it.
The average garage shop air tank compressor for weekend mechanics is usually a 20 gal 5hp.
Good enough for air tools, filling tires, and easy to store in a 2 car garage.
You must have a larger tank to hold vacuum 29hg for 2 hours using a venturi pump !
The venturi pump needs a minimum of 75psi-Porsche says to vacuum for 1 hour. The home air tank compressor I mentioned will not hold this pressure. It will start at 90psi tank or you can go up to 110psi---but after 10 minutes with the venturi pump, the tank pressure will drop to 70 and below.
The other drawback with a home compressor is the dam noise you hear for the hour.
I do not do AC repair for a living and like you mentioned, it is not economical to buy a $300 vacuum pump. Harbor Freight 2.5cfm vacuum pump has a 1 year guarantee. I feel if it works out of the box and I used it now 4 times to vacuum my AC---it will work the next time if I change the pump oil every year or so. I do consider this a limited use tool and am satisfied with the product. A professional should upgrade.
I take my repairs seriously and do not cut corners on research, parts, proper procedures or tools.
My $.02
John_AZ
1988 924S 60K + 1987 924S 113K + 1998 Cherokee 122K
1979 924 + 1977.5 924 + 1970 914 .17 + MG Midget + Audi +++===Gone past tutors
08-17-2009, 10:23 AM
#22
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You're right - many home compressors aren't big enough, but mine isn't huge. 60-gallon IR with a 5hp 100% duty cycle 220v motor. It can't keep up unless I regulate the pressure, which is why I mentioned it.
I've been through several of those HF vacuum pumps. First one was the cheap one (I think I paid $50 for it when it was on sale). Didn't last the first use. Couldn't get it to pull more than 15 InHg. Then I tried their 3cfm vacuum which overheated and seized (and yes, it had oil in it - but I think it was the motor that froze). They don't seem to like to be run for more than an hour at a time, and if I have a system that's been open for more than 24 hours, I vacuum for a minimum of 90 minutes.
And you have no idea how **** I am when it comes to my cars. My friends call it "Curt-ized" and give me **** about it all the time. Not that I mind
I've been through several of those HF vacuum pumps. First one was the cheap one (I think I paid $50 for it when it was on sale). Didn't last the first use. Couldn't get it to pull more than 15 InHg. Then I tried their 3cfm vacuum which overheated and seized (and yes, it had oil in it - but I think it was the motor that froze). They don't seem to like to be run for more than an hour at a time, and if I have a system that's been open for more than 24 hours, I vacuum for a minimum of 90 minutes.
And you have no idea how **** I am when it comes to my cars. My friends call it "Curt-ized" and give me **** about it all the time. Not that I mind
08-17-2009, 10:52 AM
#23
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I bought a good used Robinair vac pump for $200. Also a Robinair manifold set for $100, and Robinair electronic sniffer for another $100. So far I've used them for 3 conversions and 2 repair jobs, so their real cost is zero. All are quality pieces that I could always resell if for some reason I felt like paying a shop hundreds of dollars instead. HF stuff is generally a throwaway, and what's worse is that they are likely to fall apart in the middle of the job, on a Sunday afternoon.
08-02-2012, 01:24 AM
#25
Administrator - "Tyson"
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Someone should start looking into what it will take to convert our systems to CO2 since R134a is being phased out.........
