91 r4 system over haul

[tsr2185]

Quick background:

Truck sat for 3 years when I purchased it in 2020, and was told the AC worked. Bought in winter so no need for AC. When I finally needed it, the compressor wouldnt stay running I bough a fix-in-a-can freon kit (r134 converted system) and charged system. Low while running was 19psi, filled until around 25 psi while running on the low side until the compressor stayed running. Right when i went to check the vents for cool air, the system popped and a cloud of freon leaked out near the compressor (i think). I could not see exactly where the leak came from (no oil traces), but the compressor was too hot to touch after this happened and seemed like it wanted to seize and bog down engine after a good bit of the freon escaped. I turned ac off while truck was still running and leak stopped.

Since then, I have unplugged the compressor so i can use my defrost, and checked the orifice tube for debris. The orifice tube looked brand new, and the system still had a ton of freon left in it when i broke the fitting.

I dont know the status of the compressor, but i assumed there is just a blockage on the high side and i over filled it. So i plan to replace everything except the evaporator and condensor and just flush those. I have a good guage kit, and will buy a vacuum pump. Im looking into these kits from rockauto.com, and any input on which one to go with would be appreciated. OR, if i should just replace dryer/orifice tube/o-rings and flush anything that looks dirty? Thoughts?

I bought truck for 1000$ and will run until i need engine swap. So i dont wanna spend top dollar for OEM replacement. Id be happy if it lasts 2-3 years.

I am offshore right now so doing my research, I cannot acces truck for another 2 weeks.

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[Schurkey]

Don't buy a vacuum pump, get one "for free" via a parts-store "Loaner tool" program.

I got a vacuum pump, flush gun, orifice tube remover, fan clutch wrench kit (everything I needed except for a leak detector and manifold gauges, which I already owned) via O'Reilly's parts store.

Be VERY careful with the condenser. Easy for them to get folded fins, or packed with dirt so they don't cool the refrigerant like they should. I replaced mine even though it didn't leak--I could see the folded fins; and at 250K miles, I figured it was "done".

When it was me, I flushed the hoses/tubes, and evaporator, replaced everything else. In particular, make sure you replace EVERY O-ring or compression seal.

I ran the vacuum for hours; closed the valves, shut off the pump, and let it sit overnight. In the morning, having lost no vacuum, I ran the pump for another hour and then recharged.

 

[tsr2185]

Don't buy a vacuum pump, get one "for free" via a parts-store "Loaner tool" program.

I got a vacuum pump, flush gun, orifice tube remover, fan clutch wrench kit (everything I needed except for a leak detector and manifold gauges, which I already owned) via O'Reilly's parts store.

Be VERY careful with the condenser. Easy for them to get folded fins, or packed with dirt so they don't cool the refrigerant like they should. I replaced mine even though it didn't leak--I could see the folded fins; and at 250K miles, I figured it was "done".

When it was me, I flushed the hoses/tubes, and evaporator, replaced everything else. In particular, make sure you replace EVERY O-ring or compression seal.

I ran the vacuum for hours; closed the valves, shut off the pump, and let it sit overnight. In the morning, having lost no vacuum, I ran the pump for another hour and then recharged.

o'reily's is my place of choice. I didnt know vacuum pumps were "for free". I had planned to get one of those cheap vacuum pumps from harbor freight that run off of a air compressor. Your plan sounds pretty solid for getting it vacuumed down.

I.I.R.C., the condenser and the radiator look pretty new. From the records i got, it appears that a lot of maintenance was done to the truck in 2016.

Do you recommend any of the kits at rock auto? I dont mind remanned stuff, and I really dont mind working on the truck in another few years. I just would like AC this summer on my long road trips to work. I've never worked on AC systems. If i mess something up really bad, I just wont have AC. Simple as that, but I want to learn.

 

[Schurkey]

I don't recommend Rock Auto at all. But that's me, and other folks have had good luck with them.

I bought the installation kit and condenser that was the same brand as the compressor I installed. Figured they couldn't whine and snivel later, if there were warranty issues to be processed.

I "bought" the tools at O'Reillys, kept them for several days (advertised time limit is 48 hours, but I went beyond that) returned them for full refund. Can't be beat. Naturally, I got the compressor, installation kit, condenser, radiator, plus flush solvent, vacuum pump oil, fluorescent dye, and a second orifice tube from O'Reillys as well. (Needed the second orifice tube because I ABSOLUTELY could not install the one that came with the installation kit. The old one popped in and out easily, the replacement went in with minor difficulty, but the one in the installation kit WOULD NOT go into place unless I removed the O-ring.)

 

[Erik the Awful]

A decent single-stage vacuum pump is about $70 on Amazon. READ THE MANUAL. Mine has a cap that has to be removed when in use, but keeps gunk out of the vent during storage. Leave it on and the pump doesn't work well. If you want a true pro tool, two-stage pumps run about $150, and a name brand will run you over $200. My $70 Amazon special worked just fine. It also didn't come with the fitting required to attach my A/C gauges to the pump.

$70 vacuum pump:
www.amazon.com/ZENY-Single-Stage-Economy-Conditioner-Refrigerant/dp/B012CFTYX4/

Two-stage vacuum pump:
www.amazon.com/Robinair-15150-VacuMaster-Economy-Vacuum/dp/B000GTIR5K/

Adapter fitting:
www.amazon.com/gp/product/B00HF42BWY/

 

[GoToGuy]

A real electric powered vaccum pump, not one of those air compressor venturi imposter's.

 

[tsr2185]

To follow up, I finally got AC KINDA working, at least comfortable when 95deg outside. Tore apart, flushed all lines with 99% alcohol, replaced all orings, orifice tube, condenser, and compressor gasket seals. Vacuum with my cheap ass harbor freight air compressor operated vacuum for about 45 min, and it held a ~-35hg for 30 min. Added ~6oz PAG oil) and charged with about 32oz r134a. Got down to 52deg in vent, using cheap digital thermometer not a probe. Pressures were about 40low/255high in 95deg outside temp, and the compressor stayed running the whole time. I know my methods weren't ideal, but I wanted to try this all myself for the first time.

I am so happy to have AC finally, but I know I'm not done. During my overnight drive to go offshore, the AC worked fine, but the compressor started cycling on a off after a 2 hour trip. Not short cycling per say, but would run for 30sec, and off for 30 sec. Im chalking it up to night temps being around 70deg and it still may be undercharged. Wont know until I get home in about a week and put the gauges on it.

Thanks for all your input guys!