Full AC replacement/R134A
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Tuned
Joined: Jun 2025
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Full AC replacement/R134A
I'm replacing the entire AC system on my 1993 F-150 and will be charging it with R134A. I already know that I need to use PAG 46 oil, but I'm having a hard time finding out how much I should be using, and where all it should go. The compressor I got has 6.1 oz in it, according to the label, but I'm not sure if I need to remove it first and distribute it throughout the system. I see that the previous R12 based system used 7 oz of mineral oil, but not sure if that's how much I should be having here. Can someone help clarify this for me?
Lead Driver
Joined: Sep 2002
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From: North Texas
TSB is 11oz now. PAG is crap, use PAO 68. Non acidic is the major benefit. RED FOT for 134A.
Spend the money on a condenser upgrade. Swap the evap unless the exterior fins are clean on the blower fan side... probably are not.
What engine?
Spend the money on a condenser upgrade. Swap the evap unless the exterior fins are clean on the blower fan side... probably are not.
What engine?
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Tuned
Joined: Jun 2025
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4.9L engine. I already got all of the parts in. I ordered them from Rockauto. I ordered the GPD 9631885A kit, the Four Seasons 54541 evap core, and new lines from GPD. I picked up a few more cans of R134A at Walmart this morning. The compressor came with some 6.1 oz of PAG in it.
Lead Driver
Joined: Sep 2002
Posts: 9,520
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From: North Texas
Drain the compressor, big deal.
What condenser? If using the large tube, you will have so-so low speed performance due to the higher pressure created by 134A. Verify you have the seven bladed fan for the 4.9 too, airflow is key. Three, 12oz cans gets you to about 94% charged.
Toss in the 94+ I have outlined how to do or use at least a small tube 93 and older style.
What condenser? If using the large tube, you will have so-so low speed performance due to the higher pressure created by 134A. Verify you have the seven bladed fan for the 4.9 too, airflow is key. Three, 12oz cans gets you to about 94% charged.
Toss in the 94+ I have outlined how to do or use at least a small tube 93 and older style.
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Tuned
Joined: Jun 2025
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This is the condenser - https://www.globalpartsdist.com/prod...t-detail/3605C
I'll have to check which fan is on the truck.
I'll have to check which fan is on the truck.
Lead Driver
Joined: Sep 2002
Posts: 9,520
Likes: 2,028
From: North Texas
That cond will work well.
Took me a while of rain check waiting to finally receive my seven blade fan. Make sure the clutch is good too, the extra heat load will tax all other bits. of course verify you have a fan shroud.
Took me a while of rain check waiting to finally receive my seven blade fan. Make sure the clutch is good too, the extra heat load will tax all other bits. of course verify you have a fan shroud.
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Tuned
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The shroud is there and is in decent shape. The clutch is working, though it could use a cleaning.
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Lead Driver
Joined: Sep 2002
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From: North Texas
Oh and for first question, I usually dump excess oil into dryer. Take your time as it needs to absorb into the media. Too much into the compressor can 'slug' it. I also rotate the compressor by hand for a while after I dump in as much refrigerant as it will take with the vehicle off, obviously.
All things, pretty damned easy job. Start in A.M. and you can have it under vacuum by noon easily if you are a green horn. If you are renting a vac pump, change the oil in the thing. Also verify all Schrader valves snug, highly recommend that Nylog sealant too.
All things, pretty damned easy job. Start in A.M. and you can have it under vacuum by noon easily if you are a green horn. If you are renting a vac pump, change the oil in the thing. Also verify all Schrader valves snug, highly recommend that Nylog sealant too.
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Tuned
Joined: Jun 2025
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I've got some PAO and Nylog on order now. The fan is only the 5 blade version, so I'll swap that out next month. I had already stripped all the AC components out of the truck earlier in the week. Now I have both the evaporator and condenser installed. Guess I'll wait on the oil to do any more to it. I've got plenty other work in the meantime - reinstall the seat and seatbelts, finish with the refurbishment of the ECU and install it, then control arm bushings on the wife's minivan.
Thanks for all of your insight.
Thanks for all of your insight.
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Tuned
Joined: Jun 2025
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On the Nylog, is this just for putting on the threads, or also for the o-rings? Should I use it on the schrader cores as well? I guess the better question is, where all should I be using this?
On the control arms, I've got new rear lower control arms and both bushings for the front lower control arms. This is on a 2012 Odyssey with around 130k miles, so not too bad on the life of the original ones. Not much looking forward to that service, but I'll get it knocked out sometime soon.
On the control arms, I've got new rear lower control arms and both bushings for the front lower control arms. This is on a 2012 Odyssey with around 130k miles, so not too bad on the life of the original ones. Not much looking forward to that service, but I'll get it knocked out sometime soon.
Fleet Mechanic
Joined: Nov 2022
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You could use aluminum tape on the HVAC box.
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Tuned
Joined: Jun 2025
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Yes, that's the way I understood it as well. I have a roll of reflectix, so I might just cut ones for the front and back windows.
Thanks for the idea on using the foil tape. It'll probably hole up fine.
Thanks for the idea on using the foil tape. It'll probably hole up fine.