Urbanassault

I converted my a/c to r134a, blows Ice cold. I put 1.5 Lbs R134a in system. Pressure at 75 degrees ambient temperature with approximately 35% humidity at 2000 rpm's: 17 PSI low side, 265-270 PSI high side. I will measure the temp from vents when it gets a little warmer outside. My hand tells me that it is close to 30F degrees out of the vents, we shall see....

AK

Mines going into the shop tomorrow for the same thing. It is getting to the point were AC is needed here.

optionguru

What is the typical cost of this upgrade? I'm having constant problems with my ac blowing fuses and sticking in the number 3 fan position. When you do the upgrade do they replace all of the parts in the ac system?

Thnks,
Peter

Drew_K

I upgraded last year and it cost a few hundred dollars (around $300 as I recall). Some components do need to be replaced, but I don't think any of those would address the problem that Peter is describing.

Keith, you may already know this, but R134 doesn't cool as well as R12. It's possible that any improvement you're noticing is from having low R12 prior to the switch. I live down I-45 in Houston and just bought a pyrometer. I'm going to take some temperature measurements when the weather warms up and compare it to our 99 Camry (R134) and old Integra (R12). I'll post the results afterwards.

Drew
92 C2

Urbanassault

Dear Drew,

I have to say that you happen to also be living in one of the most difficult geographical locations for air conditioners in the Entire World.

Mine seems pretty Icy. I have converted many vehicles, at least 50, to R134a and have had comparable R12 results on most. I can tell you, however, that some vehicles are very stubborn(rare cases) and require one or more major upgrades, condenser, fan, viscous clutch, orifice tube/expansion valve, ect..., due to it being a less efficient refrigerant than r12. I have charged and repaired hundreds of R134a systems and found that "Most all cooling woes have derived from over charging R134a". You always want to start out at half the original R12 capacity and work with the gauges from there.

I'll post outlet temps tomorrow, and again this summer on a 110 degree day(that's 45C to y'all in the UK ).
Whew! must cool down with .. beer ... <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

Oops, gone too far now...... Obligatory Disclaimer:
I Do Not recommend tearing into your a/c system, yourself, if you do not feel confident in your ability and knowledge.

Urbanassault

Dear Peter,
Drew is right, it sounds like the problems you are describing are electrical, not refrigerant, related. Sounds like you have an electrical short somewhere.

Drew_K

Keith, would you mind posting a summary of how to recharge R134? Since it's a *little* hot in Houston during the summers, I'd like to be able to check and recharge it myself annually. It seems like you would hook up a hose having a gauge, then add R134 until proper pressure is reached. I'm sure it's not quite that simple though.

I'm also curious as to your procedure b/c it sounds like you may be getting better results than I am.

If you're uncomfortable posting, perhaps an email?

Thanks for any info,
Drew

Urbanassault

Sure Drew,
Checking the refrigerant charge on your 964, r134a, retrofitted a/c. Just know that these pressures are give or take due to ambient temp,relative humidity,oil charge, condenser efficiency,ect.. lets just say that our outside environment is a generic 80f degrees 35% relative humidity. Auto parts store: r134a gauges, must have r134a connectors(sometimes sold separately, can of r134a, can adapter. Valves on the gauges closed(never open high side valve on gauges!), attach the gauges to the fittings at the compressor. Start engine, switch to recirc, blower to max,a/c on temp full cold, exit cab, close doors. Rev engine via throttle body linkage to 1500-2000rpm's. look at gauges, low side should be at 15-17psi, high side 250-300. If low is pulling below 10 psi, you are low on refrigerant(add refrigerant through low side valve on gauges, quarter pound at a time. IE: don't dump the whole can in at once. If low is not pulling down below 20psi and your high side is above 300 psi , you are possibly overcharged. Not lower than 15-17psi low side, 260-290 high, in my environment, with this vehicle, all settings I have specified, seems optimal. Again @ 1500-1700 rpm's.
New Outside Environment...:100F, 37% relative humidity: 17-20psi low, 290-325 high 1500-1700 rpm's. Metal section of low side line @ compressor should be quite cold to touch and possibly sweating in both environments. hope this helps

altarchsa

So low side should be 15-17psi???? (1500 - 2000rpm, etc)

Mine must be way overcharged then because the cheap gauge that they began attaching to cans as a package deal a few years back reads 45psi in the "good" zone.

Any help would be appreciated.

Gus

Interesting - am thinking about changing to r134 - but not sure what has to be changed on the car - Have heard some folks say just the rubber rings other site more, and others site much more - Keith, you seem to really be up on this - What is the true story on what needs to be changed to convert to r134 - on the 964 - I have a 91 C2 Cab so to a degree it is not a major issue not to have - but sure helps on those really hot days -thks, Gus

Metal Guru

Pressure, whether it be high side or low side, is dependent on ambient temperature. Pick up the Bentley "Without Guesswork" book to get the charts for high and low side pressure vs. ambient temperature.

Rocket Rob

See this thread - https://rennlist.com/forums/964-foru...to-r-134a.html

Metal Guru

More info here:
http://www.griffiths.com/shop/index....a43007fc592021

Ryan360

Rob- thanks for the thread.