Supertex
Newbie
This is long, but supplying all the info is key to resolving problems, so...A/C gurus out there, please chime in. I'm sure you'll be helping more than just me.
I just replaced my entire A/C system...what a headache. My system has always lost freon. Over the course of a year it would be all but empty, and I never knew exactly where it was leaking - turns out the A/C shop that worked on it last, put the wrong seals on the back of the compressor. That was my leak the entire time. Anyway, I knew my condenser was in bad shape...not leaking, but about half of the fins are folded over like someone got too close at the carwash, so I decided to do it right and just replace everything.
Used the Murray condenser and compressor that Oreilly's had readily available. Wanted OEM but the Delco unit was close to $300, when this one was ~$150. Also was told by a full-time mechanic that I trust, that this newer style condenser is more efficient. Never gave it another thought...just put it in. I also replaced the dryer, orifice tube, and had new hoses made because the new Delco hoses I ordered are now made from a MUCH thinner material and kinked when installed - I have TPI on this truck and the passenger bracket lays the compressor further to the passenger side to clear the TPI throttle body. The original bracket had the idler right in the center. The original hoses fit fine, but it puts a "J" bend in the suction side that the thin-wall stuff just wouldn't tolerate. I Decided I'd only replace the evap if it wouldn't hold vacuum, because my dash is cracked to **** and it wouldn't survive extraction.
Looked up and found that for my year, GM called for 40oz of R12, and 8oz of mineral oil. Just so happens my mechanic friend has some R12 stock. Now I'm stubborn, but not stupid. I knew there was a good chance I might not be able to find R12 again, so planning for the worst, I decided to use ester oil since it works with either R12 or R134a (and 152a which is an appealing option, but another discussion). I exhaustively flushed the evap and high-pressure hard line with lacquer thinner until it came out clear, and then blew it out. The new compressor came with 4 oz of PAG already in it. I drained and measured it (I was able to get 3 oz out) then started pouring in undyed ester about 4 oz at a time...slowly spinning the compressor over to flush the remaining PAG out. Did this a few times, each time being careful to measure what came out. Once I was satisfied, I put 4 oz of UV-dyed ester in it. The rest went in the new accumulator. I changed all the o-rings to be compatible with 134/PAG, and replaced my Schrader valve. I pulled it down to -30 inches, and left it pulling for about 30-40 mins, then shut the valves and pulled off the pump. It was morning, so about 85f-90f when I pulled it down. When I checked it that afternoon it had actually gained vacuum - I suppose because it was now about 108fand everything expanded. I was pretty happy with that. I left the vacuum on it for the weekend, and then Monday took it to my mechanic friend to charge it.
Well...couple of things: 1) It's been 105-110 here for the last month or so, and humid as hell. 2) My fan is an electric unit off of a 90 Z-28, and it has no shroud and sits nearly an inch away from the core (yeah, I know...can't pull in into a long line at a drive through or it'll overheat). I know it's not going to cool to 34f in those conditions. But I was seeing temps of 55-58f at the vent after charging to factory specs, and that was using a hose to cool the condenser because high-side was getting up to 300. And another thing that was bothering me...the compressor never shut off. Of course, it was jumped at the accumulator at first, but once we were done, and the switch was back in the loop, I switched it off of 'max' and waited to see if it would ever kick off. It did not. Should it?
He kept harping about the fan not being sufficient. But I have a plan to deal with that, and was more concerned with how it performed on the highway, because that takes the fan out of the equation. So I got it out on the highway, and drove it 15 mi North to a suburb, and then whipped around and came back...75 mph.
I have tinted windows...not limo, but darker than legal. On the way out, the sun was on me, and the cooling was just enough to keep me right on the edge of sweating. On the way back, the truck was closer to comfortable, but just barely. Full bore, max fan, recirc on, it never got cold in the truck, just tolerable at best. I know what these systems are capable of because I also had an '89 that would get uncomfortably cold in the truck. Granted it was a standard cab, and I'm in an extended cab now, so it's not apples to apples, but this wasn't even close to the bar set by the 89.
I did seem to notice that it didn't really feel like it was blowing as hard as it should - functional, but lacking. So I started thinking about the evap from the fan side of things and pulled the blower motor to have a look...
You can imagine my disgust. I just blew $400 on 40 oz of unobtainium R12 and got 30 miles out of it, because now I have to put an evap in it.
I tried blowing it out from the heater core side, but the evap is way to thick for that to work. And BTW...I don't care what ANYONE says...do not try to remove the center section (just above the heater core) of the HVAC box with the dash in place. You MIGHT get it out, but it will be cracked or broken, and there is no way in HELL you're going to get it back in right. Just pull the dash...trust me, it's way, way easier - especially if you disconnect the junction block from the driver's firewall and pull the whole harness with it. You can leave the entire dash intact. I had 7 connections behind the glove box. There's also 1 at the back of HVAC controller, and several that are clipped into the terminal block and steering column, but all reasonable to get to. The only pain is the antenna wire, as it runs through a track along the lower edge of the dash - you'll have to open the track to get it out. 2 big bolts under the dash on either side of the cab, and 5 screws across the top (unless your dash looked like mine which means the 5 bolts aren't holding anything anyway. There are 2 pivot pins beneath the side bolts...the dash will pivot down and rest self-supported at an angle. You may not have to pull the column, but it's only 6 bolts and the steering shaft/shifter and it's completely out of your way...far, far easier than working around it. Remember to set the parking brake.
So out comes the dash...in pieces, of course, because mine was cracked all to hell. So dropped another $600+ on an LMC dash, paint/dye and shipping. I was going to great lengths to try to recover the R12 with the intent of reuse. Bought a recovery tank (FYI, do not buy from Vevor, and I'll just leave it at that), borrowed a recovery machine, evac'd the system, and replaced the evaporator. It's back together now, and currently sitting for it's vacuum test. I managed to score an entire case of NOS DuPont R12, so I'm covered there, but after losing $400 worth already, I'm overly concerned about loosing any more.
During this whole nightmare, I've read and learned A LOT. Several people swear by using the Ford 'blue' orifice. Also, I've also noticed that I can run the orifice tube either at the condenser exit, or the evaporator entry. It is currently in the condenser exit tube. It seems to me that the restriction should be at the evaporator, but my factory unit was in the condenser. In addition, it occurred to me that these 'high efficiency' condensers are intended for systems that use far less refrigerant by volume. The passages in them are tiny...like .040"-.060", and I'd wager that my old factory unit has at least twice the volume. My original is manifold-flow, with two passes of 3/16"-1/4" tubes, the entire height and width of the radiator core per pass. The Murray unit (which is not as deep) is top-half first pass, and the lower-half the second pass. Are they deeming these 'high efficiency' because of the heat exchange per volume ratio? I'm considering ditching the new condenser, and just ordering the larger Delco. And finally, when you evac the system, replacing the evaporator...how much oil am I loosing? I did get a tare weight on the recovery tank, and I know that what we put in was exactly 40 oz. - 2x 14 oz cans, and 1x 12 oz can. I can weigh the recovery tank, and I assume if it's 43 oz over tare, then I pulled 3 oz of oil out with the freon, but no measurable amount came out of the old evaporator. I took a blind stab and added 2 more oz of ester to the accumulator.
So my questions are:
1) Is there a benefit to using the Ford orifice tube?
2) Which is the better location for the orifice - condenser or evap?
3) If I use the prescribed 40 oz of R12, am I at risk of overcharge, given the condenser is intended for R134a conversions (albeit 'compatible' with R12)?
4) Should I just replace the Murray condenser with a Delco original style if I intend to stick with R12?
5) How do I determine how much more oil to add to the system?
6) Just by chance, has anyone used R152a?
I just replaced my entire A/C system...what a headache. My system has always lost freon. Over the course of a year it would be all but empty, and I never knew exactly where it was leaking - turns out the A/C shop that worked on it last, put the wrong seals on the back of the compressor. That was my leak the entire time. Anyway, I knew my condenser was in bad shape...not leaking, but about half of the fins are folded over like someone got too close at the carwash, so I decided to do it right and just replace everything.
Used the Murray condenser and compressor that Oreilly's had readily available. Wanted OEM but the Delco unit was close to $300, when this one was ~$150. Also was told by a full-time mechanic that I trust, that this newer style condenser is more efficient. Never gave it another thought...just put it in. I also replaced the dryer, orifice tube, and had new hoses made because the new Delco hoses I ordered are now made from a MUCH thinner material and kinked when installed - I have TPI on this truck and the passenger bracket lays the compressor further to the passenger side to clear the TPI throttle body. The original bracket had the idler right in the center. The original hoses fit fine, but it puts a "J" bend in the suction side that the thin-wall stuff just wouldn't tolerate. I Decided I'd only replace the evap if it wouldn't hold vacuum, because my dash is cracked to **** and it wouldn't survive extraction.
Looked up and found that for my year, GM called for 40oz of R12, and 8oz of mineral oil. Just so happens my mechanic friend has some R12 stock. Now I'm stubborn, but not stupid. I knew there was a good chance I might not be able to find R12 again, so planning for the worst, I decided to use ester oil since it works with either R12 or R134a (and 152a which is an appealing option, but another discussion). I exhaustively flushed the evap and high-pressure hard line with lacquer thinner until it came out clear, and then blew it out. The new compressor came with 4 oz of PAG already in it. I drained and measured it (I was able to get 3 oz out) then started pouring in undyed ester about 4 oz at a time...slowly spinning the compressor over to flush the remaining PAG out. Did this a few times, each time being careful to measure what came out. Once I was satisfied, I put 4 oz of UV-dyed ester in it. The rest went in the new accumulator. I changed all the o-rings to be compatible with 134/PAG, and replaced my Schrader valve. I pulled it down to -30 inches, and left it pulling for about 30-40 mins, then shut the valves and pulled off the pump. It was morning, so about 85f-90f when I pulled it down. When I checked it that afternoon it had actually gained vacuum - I suppose because it was now about 108fand everything expanded. I was pretty happy with that. I left the vacuum on it for the weekend, and then Monday took it to my mechanic friend to charge it.
Well...couple of things: 1) It's been 105-110 here for the last month or so, and humid as hell. 2) My fan is an electric unit off of a 90 Z-28, and it has no shroud and sits nearly an inch away from the core (yeah, I know...can't pull in into a long line at a drive through or it'll overheat). I know it's not going to cool to 34f in those conditions. But I was seeing temps of 55-58f at the vent after charging to factory specs, and that was using a hose to cool the condenser because high-side was getting up to 300. And another thing that was bothering me...the compressor never shut off. Of course, it was jumped at the accumulator at first, but once we were done, and the switch was back in the loop, I switched it off of 'max' and waited to see if it would ever kick off. It did not. Should it?
He kept harping about the fan not being sufficient. But I have a plan to deal with that, and was more concerned with how it performed on the highway, because that takes the fan out of the equation. So I got it out on the highway, and drove it 15 mi North to a suburb, and then whipped around and came back...75 mph.
I have tinted windows...not limo, but darker than legal. On the way out, the sun was on me, and the cooling was just enough to keep me right on the edge of sweating. On the way back, the truck was closer to comfortable, but just barely. Full bore, max fan, recirc on, it never got cold in the truck, just tolerable at best. I know what these systems are capable of because I also had an '89 that would get uncomfortably cold in the truck. Granted it was a standard cab, and I'm in an extended cab now, so it's not apples to apples, but this wasn't even close to the bar set by the 89.
I did seem to notice that it didn't really feel like it was blowing as hard as it should - functional, but lacking. So I started thinking about the evap from the fan side of things and pulled the blower motor to have a look...
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You can imagine my disgust. I just blew $400 on 40 oz of unobtainium R12 and got 30 miles out of it, because now I have to put an evap in it.
I tried blowing it out from the heater core side, but the evap is way to thick for that to work. And BTW...I don't care what ANYONE says...do not try to remove the center section (just above the heater core) of the HVAC box with the dash in place. You MIGHT get it out, but it will be cracked or broken, and there is no way in HELL you're going to get it back in right. Just pull the dash...trust me, it's way, way easier - especially if you disconnect the junction block from the driver's firewall and pull the whole harness with it. You can leave the entire dash intact. I had 7 connections behind the glove box. There's also 1 at the back of HVAC controller, and several that are clipped into the terminal block and steering column, but all reasonable to get to. The only pain is the antenna wire, as it runs through a track along the lower edge of the dash - you'll have to open the track to get it out. 2 big bolts under the dash on either side of the cab, and 5 screws across the top (unless your dash looked like mine which means the 5 bolts aren't holding anything anyway. There are 2 pivot pins beneath the side bolts...the dash will pivot down and rest self-supported at an angle. You may not have to pull the column, but it's only 6 bolts and the steering shaft/shifter and it's completely out of your way...far, far easier than working around it. Remember to set the parking brake.
So out comes the dash...in pieces, of course, because mine was cracked all to hell. So dropped another $600+ on an LMC dash, paint/dye and shipping. I was going to great lengths to try to recover the R12 with the intent of reuse. Bought a recovery tank (FYI, do not buy from Vevor, and I'll just leave it at that), borrowed a recovery machine, evac'd the system, and replaced the evaporator. It's back together now, and currently sitting for it's vacuum test. I managed to score an entire case of NOS DuPont R12, so I'm covered there, but after losing $400 worth already, I'm overly concerned about loosing any more.
During this whole nightmare, I've read and learned A LOT. Several people swear by using the Ford 'blue' orifice. Also, I've also noticed that I can run the orifice tube either at the condenser exit, or the evaporator entry. It is currently in the condenser exit tube. It seems to me that the restriction should be at the evaporator, but my factory unit was in the condenser. In addition, it occurred to me that these 'high efficiency' condensers are intended for systems that use far less refrigerant by volume. The passages in them are tiny...like .040"-.060", and I'd wager that my old factory unit has at least twice the volume. My original is manifold-flow, with two passes of 3/16"-1/4" tubes, the entire height and width of the radiator core per pass. The Murray unit (which is not as deep) is top-half first pass, and the lower-half the second pass. Are they deeming these 'high efficiency' because of the heat exchange per volume ratio? I'm considering ditching the new condenser, and just ordering the larger Delco. And finally, when you evac the system, replacing the evaporator...how much oil am I loosing? I did get a tare weight on the recovery tank, and I know that what we put in was exactly 40 oz. - 2x 14 oz cans, and 1x 12 oz can. I can weigh the recovery tank, and I assume if it's 43 oz over tare, then I pulled 3 oz of oil out with the freon, but no measurable amount came out of the old evaporator. I took a blind stab and added 2 more oz of ester to the accumulator.
So my questions are:
1) Is there a benefit to using the Ford orifice tube?
2) Which is the better location for the orifice - condenser or evap?
3) If I use the prescribed 40 oz of R12, am I at risk of overcharge, given the condenser is intended for R134a conversions (albeit 'compatible' with R12)?
4) Should I just replace the Murray condenser with a Delco original style if I intend to stick with R12?
5) How do I determine how much more oil to add to the system?
6) Just by chance, has anyone used R152a?
