93 Complete A/C system replacement - Questions for gurus

[Supertex]

Even going down the road, I rarely see better than 45-42 so far. Given that we're probably 40% humidity and as of this moment 110°, maybe 40's isn't so bad?

I've been watching what you post pretty carefully. You seem to know your stuff. I paid special attention to your recent comment to someone about their recirculation door and sealing condition. My door works, but it doesn't seal. There are gaps on both sides... Not huge but at least 3/16 of an inch. Given that this is the first time I've torn something like this apart this far, I'm not sure I'm qualified to really say, but it appears that's the way this was from the factory. It's hard for me to tell because I'm also missing about a two and a half inch long and half inch wide strip from one edge. I know that's going to have to get fixed if I want the temps to really come down.

I thought perhaps in the interim since I need to remove and clean my windshield washer jets, that I might block off the outside air intake while I have the cowl cover off...see how much difference that makes.

Prior to recently, I had the 28-in radiator and an electric fan off of a Z28. Well I had everything torn apart, I noticed the radiator was leaking, so I opted to replace it with the 34" big block radiator. I found an appropriate shroud, but I'm using a five blade fan as you mentioned.

What is your take on that blue Ford orifice?

 

[cjcb1100]

i have the red sitting here just gotta buy some more refrigerant , i know your not talking to me. i think the red while not my idea will work well with my low idle and pump im using

 

[L31MaxExpress]

Even going down the road, I rarely see better than 45-42 so far. Given that we're probably 40% humidity and as of this moment 110°, maybe 40's isn't so bad?

I've been watching what you post pretty carefully. You seem to know your stuff. I paid special attention to your recent comment to someone about their recirculation door and sealing condition. My door works, but it doesn't seal. There are gaps on both sides... Not huge but at least 3/16 of an inch. Given that this is the first time I've torn something like this apart this far, I'm not sure I'm qualified to really say, but it appears that's the way this was from the factory. It's hard for me to tell because I'm also missing about a two and a half inch long and half inch wide strip from one edge. I know that's going to have to get fixed if I want the temps to really come down.

I thought perhaps in the interim since I need to remove and clean my windshield washer jets, that I might block off the outside air intake while I have the cowl cover off...see how much difference that makes.

Prior to recently, I had the 28-in radiator and an electric fan off of a Z28. Well I had everything torn apart, I noticed the radiator was leaking, so I opted to replace it with the 34" big block radiator. I found an appropriate shroud, but I'm using a five blade fan as you mentioned.

What is your take on that blue Ford orifice?

My go to is the Red Ford orifice tube on GMs with R134a or R152a. It is a 0.062" rather than the GM 0.072". The Blue is 0.067".

 

[Supertex]

A6 compressor? In your '93 GMT400 truck? That would be an R4 sir

Richard

Indeed, sir. I get axial and radial mixed up all the time...I just hate the way "pancake" sounds, heh.

 

[someotherguy]

Indeed, sir. I get axial and radial mixed up all the time...I just hate the way "pancake" sounds, heh.

Most folks don't care for the obnoxious noises they're known for.

Richard

 

[GoToGuy]

Well for what is worth, I posted earlier about the helpful neighbor breaking the AC casting bracket. So after new after new ACDelco compressor, new accumulator, oil, vacuum down. Serviced, as first can was charging compressor kicked on fast cycling. Continued full time between compressor cycle time , longer and longer. Filled to charted charted pressures. Temp in center vents 52 ° F , for a 103° day, 38% humidity at idle. Test drive down highway 44° F.
Two days later, take wife to after surgery follow-up. Another 106° F day. Over to Bay area, appt stop, and back lowest observed temp 38° F. Still have to back blow radiator and condenser, and check clean cab HVAC fan chamber. Maybe improve effecency a little more.
Yes it's science in a head to head compare R134, is not as efficient as R12. But the EPA made that the new standard.
I had no idea when the new snap on machine for 1234a showed up, it would be , I was told this $ 1000. 00 to service.

The other problem is like many regulatory, oversight organizations the sell a good game with " we only set the bar to here, that's OK right?" Then the next tactic is now every one is complacent and they quietly keep moving the bar farther away. As in Calif. Diesel was exempt from smog. Any vehicle older than 20 years exempt. There are few others, that really affected some hotrod guys that rules changed halfway through projects.
Now the proposal is taxing vehicles per mile driven.

 

[L31MaxExpress]

Most folks don't care for the obnoxious noises they're known for.

Richard

I care for the squealy noises the belts make when they lockup even less.

 

[Road Trip]

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.

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Supertex,

Thanks for writing up your problem statement so clearly & including all the necessary detail. I say this
because I've been thinking about bringing the A/C back to life on my truck, but if I do so I want
the performance to be as good as new.

And your evap photo is very persuasive. I'll bet a dollar that mine is similar, so the A/C restoration
calculus has to factor in replacing the evap too. (And of course the dash R&R that goes with it.)

Bottom line, if I stay in upstate NY I'll leave well enough alone. But if I were to move back to TX
I would absolutely make it right before I depart for saner pastures. (!)

So, yeah, I'll be watching this unfold with interest. Good luck getting it blowing a little concert-style
cold fog out the vents!

 

[Supertex]

Thanks for writing up your problem statement so clearly & including all the necessary detail.

No one has ever accused me of brief =P.

Since my last, I've added the dual 16" (?) fan and shroud off a 95. Wow. Kinda hard to shell out $350 for a shroud/fan combo and then immediately start cutting on it, but it turned out pretty nice. Of course I had to get Dakota Digital's 70 amp relays, and a gob of 8 and 12 ga silicone jacketed wire. The fans pull ~22 amps once they're up to speed, but I saw the amp gauge hit 50+ briefly on startup. I've got 30 amp fuses in it right now, and frankly, Im surprised it doesn't pop them. They get hot enough to slightly deform, but they do no discolor. Considering moving to 40A's. I probably should have used 10ga for the fan runs, but hopefully the high-quality 12 ga will suffice. Problem now is going to be alternator. At night with the AC on full blast, both fans running, and lights, at idle, my voltage drops to ~11.8. but even at 1200 rpm, it jumps up to 12.2. and at cruise it maintains 12.8 volts. I have my eye on a 320a Mechman 712730...those are hella expensive, but they may good power at low speeds. Alternatively, the 200a Powermaster 47806 may be decent. Leaning toward Mechman, as I have amps waiting to be installed too.

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With both fans running, my overheating in the Whataburger line days are over with, and I get the same temps from the vents as I get on the highway. Just one of the two was marginally better than the clutch fan and shroud I'd put on recently, but it wasn't enough to keep it at highway performance levels. To be fair though, my clutch fan wasn't new. It had lots of resistance with the engine off, but I couldn't rev over 3k without vibration, so there was an issue with it. And of course, I realize that just running one fan was pulling a non-trivial amount of air in from the engine-side of the adjacent fan, but I only had wiring for one before I dug into it.

I'd also bought some neoprene weatherstrip-type material that I'd intended to use for sealing the condenser to the radiator, and blocking off above and below the condenser. The idea was to wait and see how much difference there was between highway cooling figures and idle. However, with these fans, I don't think there's anything to gain, given that hwy and idle temps are the same. The coldest I've seen the vents is 45, and if it's 108-110, the temps are 48-50.

So, at this point, the next couple of things to square away is my recirculation door, and the hole in the firewall my antenna runs through. The lunkheads that swapped in my 4L80E ran the controller grounds through that hole by pulling out the grommet, and never even pushed it back close to the hole. That of course left a half-dollar size hole that blows under hood air RIGHT under the recirculation intake. Couple that with the mouse-chewed recirc valve...

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I'm hoping that between solving `these two items, I can get close to 40 degree temps, but that might be over-ambitious. I've located two sources for blower motor housings, one with no dash, and another I'll have to tear into. With just 4 bolts inside and 3 under the hood, I'm hoping I can avoid having to pull or loose the dash again. I'm really sick of messing with the dash. We'll soon see.

 

[L31MaxExpress]

No one has ever accused me of brief =P.

Since my last, I've added the dual 16" (?) fan and shroud off a 95. Wow. Kinda hard to shell out $350 for a shroud/fan combo and then immediately start cutting on it, but it turned out pretty nice. Of course I had to get Dakota Digital's 70 amp relays, and a gob of 8 and 12 ga silicone jacketed wire. The fans pull ~22 amps once they're up to speed, but I saw the amp gauge hit 50+ briefly on startup. I've got 30 amp fuses in it right now, and frankly, Im surprised it doesn't pop them. They get hot enough to slightly deform, but they do no discolor. Considering moving to 40A's. I probably should have used 10ga for the fan runs, but hopefully the high-quality 12 ga will suffice. Problem now is going to be alternator. At night with the AC on full blast, both fans running, and lights, at idle, my voltage drops to ~11.8. but even at 1200 rpm, it jumps up to 12.2. and at cruise it maintains 12.8 volts. I have my eye on a 320a Mechman 712730...those are hella expensive, but they may good power at low speeds. Alternatively, the 200a Powermaster 47806 may be decent. Leaning toward Mechman, as I have amps waiting to be installed too.

You must be registered for see images attach

With both fans running, my overheating in the Whataburger line days are over with, and I get the same temps from the vents as I get on the highway. Just one of the two was marginally better than the clutch fan and shroud I'd put on recently, but it wasn't enough to keep it at highway performance levels. To be fair though, my clutch fan wasn't new. It had lots of resistance with the engine off, but I couldn't rev over 3k without vibration, so there was an issue with it. And of course, I realize that just running one fan was pulling a non-trivial amount of air in from the engine-side of the adjacent fan, but I only had wiring for one before I dug into it.

I'd also bought some neoprene weatherstrip-type material that I'd intended to use for sealing the condenser to the radiator, and blocking off above and below the condenser. The idea was to wait and see how much difference there was between highway cooling figures and idle. However, with these fans, I don't think there's anything to gain, given that hwy and idle temps are the same. The coldest I've seen the vents is 45, and if it's 108-110, the temps are 48-50.

So, at this point, the next couple of things to square away is my recirculation door, and the hole in the firewall my antenna runs through. The lunkheads that swapped in my 4L80E ran the controller grounds through that hole by pulling out the grommet, and never even pushed it back close to the hole. That of course left a half-dollar size hole that blows under hood air RIGHT under the recirculation intake. Couple that with the mouse-chewed recirc valve...

You must be registered for see images attach

I'm hoping that between solving `these two items, I can get close to 40 degree temps, but that might be over-ambitious. I've located two sources for blower motor housings, one with no dash, and another I'll have to tear into. With just 4 bolts inside and 3 under the hood, I'm hoping I can avoid having to pull or loose the dash again. I'm really sick of messing with the dash. We'll soon see.

Put an adjustable cycling switch on it. The R12 switches short cycle with R134a. R134a and R152a for that mattter need to get to a lower pressure before the compressor cycles to get the evaporator temps nearer freezing. I have seen the van briefly pull 27°F vent temps in 108-110°F before the compressor cycles at highway speeds. It usually resides around 31-33°F, once the interior has cooled off. I have gone an 1/8 turn too much before on the van and turned the evaporator core into a solid block of ice every 5-10 minutes requiring switching to vent to thaw it out and get the vents blowing again.