AC R134 Converted: Trouble Shooting

[GrandW]

Hi All - could use a hand here. The PO of the 87 GW had the AC converted to R134, which is great. Here's a picture of the valves. Am I correct that the gold valve is the High Side port, and the silver valve on top is the low side port? Also is the silver valve supposed to appear sealed like that?

I've read the TSM and done some searches to determine if it's just low on R134, and I can't see any bubbles in the site glass... but the it's my 1st time trying this. Is there any danger in just adding a can of R134? I don't want to blow it out by overfilling.

[will e]

It's hard to tell from the picture. The high side will go to the evaporator in the cab. I believe this is the top hose in your picture just looking at the most likely routing. << Edit This is wrong. See next post.

[SJTD]

Yeahbut, high side goes to the condenser, and the drier and the sight glass before going to the cab. Usually smaller line too. Low side is a straight shot from the evaporator to the pump.

[will e]

Darn it! I always get that backwards in my head. Yeah, SJTD is right. The refrigerant is compressed so it reaches a temp higher than the outside temp. It is then sent to the condenser where the outside temp removes some of the heat.

[SJTD]

I never did answer your question. Looks weird to me, never seen a valve like that nor a cap on the fitting like that. Should see the valve in there. Is that soft like a rubber plug?

[GrandW]

The silver plug insides feels hard, like someone filled it with JB Weld. The hose from that one runs straight back towards the dash (green line). The gold one below, loops back to the front (white line).

The silver plug has to be cleaned out or there's no way to check the low side pressure. My take is either invest in a full test kit, or take it to a pro. I'd guess there's a leak somewhere or it would blow cold. Argh. Here I was thinking it was done.

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[SJTD]

What's the high side port look like? I wonder if that one was leaking and that was their fix.

I wonders if you took that adapter off if the Shrader valve in the R12 fitting is still there. If so you could just replace the adapter. Probably not. Prolly loose whatever gas is left in there.

But, you could front seat the valves and only loose what's in the pump itself. BUT the high side hose looks like it's where the valve stem should be.

[GrandW]

Good call. Went ahead and removed the valve with hopes of cleaning it out... going to just need a new valve. No R134 was in the system, and here's what it looks like once off.

Tried to smoke test it, no luck. Best I can tell next steps are to vac the system, add dye and R134, run, look for leaks. If leaks, fix leaks (doubt this is easy or cheap), vac, add R134.



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[ghcoe]

If you did not hear some gas escape when you removed the valve I would replace the Drier as well. Also, I would recommend just changing out the condenser to a 134A unit too. I changed mine out for a universal unit about the same size. Made a huge difference in idle cooling. You would have to change out the fittings though. I was under $75.00 with parts and charge.

Oh, I should mention you probably should flush the system too. You can find how too's on YouTube. My first attempt at 134A conversion worked well till the old oil in the system clogged up the evaporator. I though I had a bad pump since it would lock up. Turns out it was just gunk settling in the low part of the system. They may not have done that when they converted. Just saying...

[GrandW]

Thanks ghcoe.

Got the system vacuumed and no leaks. Getting ready to add 134, but from what I've read the pulley on the compressor is supposed to "engage".

This front part (green circle) spins by hand, but not when the AC is on, or off. Does this mean my compressor isn't working right? AC system has no refrigerant.



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[sirrus]

Center piece of pulley is attached to compressor and there is a electromagnetic clutch that connects it to the outside part of the pulley. You can test the clutch by putting 12 volts on the clutch wire (top of the compressor) with engine off. It makes quite a loud sound when it engages.

There is a low pressure switch on the pass side fender near sight glass that opens when pressure is low and would prevent clutch from engaging when there's no refrigerant

This front part (green circle) spins by hand, but not when the AC is on, or off. Does this mean my compressor isn't working right? AC system has no refrigerant.

Does it spin by hand when it's on or off? Or both?

[GrandW]

It spins by hand when off. I can't test it when it's on because the fan blade is to close. Applied a ground wire to the black wire coming out of the compressor and it clicks. So it seems to have the ability to work.

Rookie question, when connecting these tubes from the vacuum gauge to the ports. Are these ports supposed to be tightened down (turned clockwise), or left open? If I turn them counterclockwise the vacuum doesn't get close to 0, indicating I'd have a massive leak. Wondering if I'm using it right.

From what I gather, the compressor won't engage if there's no R134a.

[sirrus]

Oh, I wasn’t sure what did you mean was on/off - engine or clutch definitely don’t try to rotate it with your hand on running engine.

To get a reading from gauges you need to open the valve in your pic to connect the gauge to ac system. Otherwise you’d be measuring pressure in the hose. Valve on the other side of the hose (by gauges) is connecting blue or red hoses to middle one (yellow). For measurements those should be close, you open them for vacuuming or charging

And yes, with no refrigerant the low pressure switch would be open and prevent compressor clutch from getting energized.


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[SJTD]

I don't know if you know how to operate the service valves on the compressor; that square ended shaft. It has three positions. All the way CW isolates the pump from the system and is used when removing it. All the way out is the normal position and closes off the service ports so even if they leak you don't loose any gas. Between those two positions is where you want to be to charge it.

[GrandW]

You're right, it had me confused. Got it sorted, all charged up, and now it leaks out the high side port valve when I removed the gauge I guess one should somehow leak test the valves.

Got to figure out how to responsibly remove the R134, then replace that valve, recharge etc.

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[sirrus]

Does it mean that you can block off the high side valve by turning the service valve all the way CCW and replace that valve on a charged system? That’d be neat

As for evacuating R134 - any AC shop should be able to do it. It is illegal to intentionally vent refrigerant to atmosphere


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[SJTD]

Yeabut from the pichers it doesn't look like he has the original high side valve. It looks like the test port is where the valve shaft should be.

[sirrus]

Yeah, looks like that - didn’t notice it at first. It’s cool that you can replace the low and high side valves without worrying about charge on stock setup


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[GrandW]

Lessons on the A/C... turns out the connectors are single use as the threads are specially coated. So once you remove it, toss it. The second lesson is the schrader valves are very sensitive, so you'll want to pop on and off the connectors are little as possible. It also might help to have a few spare schrader valves on hand, and removal tool.

Thanks for everyone's input.