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? re: not cold enough R134a conversion


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Converted to R134a around 3 months ago with new compressor, condensor, accumulator and expansion valve. Problem is, and this is in South Florida, when idlng in traffic or at a light, b/c of the decreased airflow, the A/C can get quite warm. At speed the A/C gets very cold. I know that unless the high side gets over 140 or so, the fans stay on low speed. My question is, does anyone know a way to wire,at least the front pusher fan to operate on its high speed setting to push more air thru the condenser? I think this would help a lot in regarding the A/C's ability to coll while driving at low speeds.<P>Thanks<P>Adam

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Doubt that the fan will help much with a/c at ilde, is the compressor turning too slow (mine does the same thing, 650 rpm is just too slow to cool well, you need around 1k minimum. Could either wire around the resistor on fan (puller on HIGH all of the time) or move the relay coil wire of the pusher to the puller relay output (both fans on with a/c). an alternative would be to conect the pusher in parallel with the puller (both on low with a/c) but not sure if the ballast resistor would be big enough. <P>Better alternative would be to add second ballast resistor (suspect same size OK) to pusher also connected to the low speed relay output. Keep in mind that each fan pulls 10-12 amps according to the FSM so need to be careful of cumulative loads.(why would not just connect to low side of puller ballast).<P>Cannot be more pricise at moment since both FSM and car are 4,500 miles North.

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Understand that R'134A has a lower specic weight than R-12 so the same amount as R-12 is too much and can lead to undercooling. Had our 90`Bonneville )strange keyboard) converted about a year ago and it cools just fine in Orlando.

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I converted to R134a b/c I needed a new compressor and condensor anyways. Total cost was 450$. What I have heard is that the primary difference between R12 and R134a systems is the condenser size. Larger for R134a than R12. <BR>Compressor speed is not the problem b/c revving the engine is not effective. What makes the biggest difference is high airflow thru the condensor.<BR>Also, I didn't go with one of the variable orifice tubes b/c after talking with several shops, who really knew nothing about them, I decided that the technology was still to new to the market.<BR>Padgett, my fans are both on when the A/C is on although they are both on low. Could you please elaborate as to how I could make the puller and possibly pusher fan both go to high when the A/C is on, but stay on low when the A/C is not on but the engine needs their cooling.<BR>Thanks for the replies<P>Adam

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There aren't any resistors involved in the fan speeds as far as I can see. They are wired to operate in series for low speed and parallel for high speed, that's done using three relays. One fan should never operate by itself. The computer commands the fan speeds so unless you hot wire them with switch. You can also use the fan overides in the diagnostic mode to operate them manually.

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Regarding air conditioning conversion from R12 to R134A: Don't do it!<P>Freon 12 is in plentiful supply and will be for many years to come and still is reasonably priced, about $10 a pound. Any old free refrigerator can be transfused to net seveal pounds of R12.<P>The problem is the new R134A just doesen't have the high cooling capacity as the old R12. That's fine if the system was designed for R134A. It will have a larger condenser, evaporator, higher capacity compressor, as well as different composition hoses. The problem occurs when the R12 system is converted to R134A using the same components. The result is lack of cooling.<P>Why convert over for $500-$1000 with inferior cooling when a couple pounds of R12 and servicing cost $100? Stick with R12. smile.gif" border="0

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It sounds like the cooling fan system in my 88 is different from that in the 90. In the 88 only the puller is on at low speed - through a ballast resistor at low (low speed relay) and direct in high (middle relay). Pusher is only on (end relay) when puller is in "high". My wife's '90 Bonneville (converted to 134 & works fine) is the same.<P>However since you are the second person to mention both fans on in low I must assume that sometime between 88 and 90 the Reatta system was changed.<P>Can also say that on a hot day the cooling drops off at idle and pick up if you raise the revs to 1000 or so. Bonne is less so but it idles at 900 rather than the reatta's 650, hence my feeling that at low idle the compressor is not turning fast enough since fan operation is independant.

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DO NOT COVERT TO R134A ... THERE IS A NEW FREON THAT WILL BE OUT LATER THIS FALL,IT IS COMPATABLE WITH R12..YOU WILL BE ABLE TO JUST MIX IT RIGHT IN..NO CHANGING OF DRYER,OIL OR ANYTHING...<P>BCP

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It is impossible for a system designed for R12 to work as well on 134a. The characteristics of the refrigerents are immutable. GM says the lost cooling capacity in a back fitted R12 system is not noticed "under most conditions". I don't believe idling in traffic on a 96 degree day in Central Florida after getting into a car parked in the sun all day falls under "most conditions". The Reatta AC is marginal in the first place. Converting to 134a makes it downright unlivable in really hot climates.<P> Stay with the R12. Also, there have been "drop in" refrigerents marketed since the R12 ban. All the ones that really work well are propane or some other explosive gas based. The Internet is full of claims from those who have discovered the "Holy Grail" <BR>of a direct drop in replacement. Any one who has replaced any part of a Reatta AC system knows what the parts cost. It dosen't make good sense to experiment with our increasingly hard to repair systems.

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2seater, How do I go about manually operating the fans on high speed for a 1990 using the diagnostic mode. I shouldn't put a jumper between the A and B pins while I'm driving, should I? Also, I could just run a wire, through a switch in the passenger compartment from the batt. to the fan and flip it while the AC is on? Would this make the fans run on high speed?<BR>Thanks<P>P.S. Padgett, I don't think prob. is slow compressor speed b/c increasing the revs does not increase the cooling. Only thing that increases the cooling is increased airflow thru the condensor, and then it is ice cold smile.gif" border="0<BR>Adam

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Has anyone tried the hydrocarbon refrigerants? These are a combination of propane and isobutane. They operate on less head pressure and take only 30 - 40% the amount of R 12 and are compatible with the refrigerant oil. I have not used in my Reatta yet, but have in other vehicles.

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Jhellman, <P>1. It's ILLEGAL to use isobutane, propane or any flammible gasses in a car's A/C system. Period, end of sentence, unless you like paying $10,000 fines to Uncle Nosey Sam. <P>2. Let's see....what happens when your car has a frontal collision (about 85% of car crashes are frontal) and you break a line or the condensor? What is that word I'm looking for when a mixture of pressurized propane, isobutane, and possibly gasoline leaking from a broken fuel rail mix with a hot exhaust manifold, sparks from exposed wires shredded in an accident, or maybe just the driver's cigarette??? Oh, yeah....a BOMB...that's the word I'm looking for. <P>Do us all a favor and report any jackass proposing to use explosive gasses under pressure in a car's A/C system to the local bomb squad. Don't want to see you on CNN from a helicopter circling the burning building that used to be your house or office. <P>Joe

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ES07 in the ECM overide mode turns both fans on low. ES08 turns on the pusher fan (alone) at high speed. Unfortunately it is not possible to operate both fans on high unless you hot wire them, or the ECM energizes all three relays.

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  • 3 weeks later...

Redreattaruss..My a/c man tells me R22 is in refrigerators and that will destroy an r12 system Also would like to know where you get R12 for less than $60 a can. I live in Fl and my first 90 has been converted with no problems. I'm about to have another 90 converted..need new compressor anyway. Is an oversized condensor worth considering?

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Well, I converted mine 'cause I needed a new compressor and I regret it. I have the same problem with airflow. The rpm isn't the problem, it helps but the only thing that makes it cold is condenser airflow. I'll have to try the fan speed change, it is probably necessary for a retrofitted system. I'll try it this weekend and let you all know what happened.

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As mentioned, wife's '90 Bonne converted to 134 will freeze you out but needs at least 1200 rpm for max effect. Also noted that as soon as it starts the low engine fan is on but switches to high fan within 30 seconds. Coolant temp stays on thermostat opening (measured with scan tool) & air is cold (just not freezing) even with 30 minutes of idling at 92+F.

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