new install charging problem

[msrichmond]

Can you define "open" and "closed"?

On the MGS, clockwise is closed, CCW is open.

On the can tap and on the service ports (which do have thumbwheels), I define open as "pointy thing sticks out to depress schrader valves". In both cases, turning those clockwise makes the pointy end stick out. I took back a can tap that had instructions like "turn clockwise all the way then back it off". Could not get it to work. Back off how much? Then I bought one with a plastic thumbwheel that just says turn clockwise.

If I have all this bass-ackwards, it would definitely give me bad results.

[JohnHere]

Can you define "open" and "closed"?
On the MGS, clockwise is closed, CCW is open.

You are correct on the handwheel rotation of the MGS valves.

On the can tap and on the service ports (which do have thumbwheels), I define open as "pointy thing sticks out to depress schrader valves". In both cases, turning those clockwise makes the pointy end stick out.

Again correct. Unlike the older style "tapper valve" that actually pierces the top of the can with CW rotation and then starts refrigerant flow with CCW rotation, you have a current can tap with valving in the can that automatically shuts-off refrigerant flow with CCW rotation and starts flow with CW rotation. In a similar fashion, your service-port adapters depress and open the Schrader valves with CW rotation of the thumbwheels.

[msrichmond]

I called the vendor of my evaporator unit and talked to tech support. He basically said that my charging process was wrong.

First, he said I have been looking at the blue gauge, seeing 50PSI and expecting the compressor to come on. He said that I need 30+ PSI on the *high* side for the compressor to come on. I told him I could not get any reading on the high side with the R134a I got in from vacuum and he said I should be jumpering the trinary switch to force the compressor on and to get 28+ ounces in with the compressor running.

Agreed?

[JohnHere]

I called the vendor of my evaporator unit and talked to tech support. He basically said that my charging process was wrong. First, he said I have been looking at the blue gauge, seeing 50PSI and expecting the compressor to come on. He said that I need 30+ PSI on the *high* side for the compressor to come on.

I don't think your charging process was wrong. Additionally, you weren't looking at only the LS gauge. You were looking at both gauges and quickly determined that there was no pressure building on the HS after attempting to charge it—certainly a legitimate concern.

But yes, you do need a certain amount of pressure on the high side to overcome the low limit of the trinary switch for the compressor to engage. But I would opine that charging refrigerant gas into the low side should also charge the high side at the same time if everything is working as it should.

I told him I could not get any reading on the high side with the R134a I got in from vacuum and he said I should be jumpering the trinary switch to force the compressor on and to get 28+ ounces in with the compressor running. Agreed?

Normally, there's no need to jumper anything, and I don't advocate jumpering a safety switch. First, it's there for some very good reasons: To protect the compressor from running without sufficient refrigerant, and to prevent a burst hose, or worse, should the compressor continue running unchecked and building pressure beyond safe limits. Second, defeating the switch and forcing the compressor to run without enough refrigerant, which also carries the oil, will "starve" the compressor for lubrication at the beginning and probably lead to its early demise. It's similar to running an engine with little to no oil.

That said, you could try jumpering the trinary switch, forcing the compressor to run, and then attempt to charge it. But IMHO, you'll risk destroying the compressor. Besides, you won't charge the system into the HS anyway for the reasons previously mentioned.

[msrichmond]

I called the vendor of my evaporator unit and talked to tech support. He basically said that my charging process was wrong. First, he said I have been looking at the blue gauge, seeing 50PSI and expecting the compressor to come on. He said that I need 30+ PSI on the *high* side for the compressor to come on.

I don't think your charging process was wrong. Additionally, you weren't looking at only the LS gauge. You were looking at both gauges and quickly determined that there was no pressure building on the HS after attempting to charge it—certainly a legitimate concern.

But yes, you do need a certain amount of pressure on the high side to overcome the low limit of the trinary switch for the compressor to engage. But I would opine that charging refrigerant gas into the low side should also charge the high side at the same time if everything is working as it should.

I told him I could not get any reading on the high side with the R134a I got in from vacuum and he said I should be jumpering the trinary switch to force the compressor on and to get 28+ ounces in with the compressor running. Agreed?

Normally, there's no need to jumper anything, and I don't advocate jumpering a safety switch. First, it's there for some very good reasons: To protect the compressor from running without sufficient refrigerant, and to prevent a burst hose, or worse, should the compressor continue running unchecked and building pressure beyond safe limits. Second, defeating the switch and forcing the compressor to run without enough refrigerant, which also carries the oil, will "starve" the compressor for lubrication at the beginning and probably lead to its early demise. It's similar to running an engine with little to no oil.

That said, you could try jumpering the trinary switch, forcing the compressor to run, and then attempt to charge it. But IMHO, you'll risk destroying the compressor. Besides, you won't charge the system into the HS anyway for the reasons previously mentioned.

All good points. Given that Autozone had a Four Seasons expansion valve in stock for $32, I'm going to replace it and see what happens. I tried in my install to offset the evaporator to the right so that the driver's side valve is accessible without totally undoing everything. We'll see how my back holds out upside down in the car.

[msrichmond]

I did not replace the expansion valve (and may not have to after all). With the blue gauge reading 50+ and with the blue valve closed, I removed the blue tap. Then I pressed the schrader valve on the low side and got a short hiss with no visible refrigerant. Then I opened the blue valve on the gauge set and the pressure dropped to zero. In other words, almost nothing is getting into the system.

When I was having trouble earlier, I called the manufacturer of the gauge set and asked what was supposed to connect to the can tap. He said "the end of the yellow hose". I connected the plain end to the gauge and the other end to the can tap. At the same time, I asked "What about the other fitting in the box? Is that for one of those big recharge tanks?" He said yes and I put it away.

This morning, with new expansion valve in hand I took another look at the hose-end accessory. It has a different fixed pin that looks like it designed to depress something in my new can tap. I think it is meant to go on the end of the yellow hose.

In other words, I don't think I've gotten any refrigerant in at all so far!

I'm pulling a new vacuum now, and I'll let you know how it turns out.

BTW, this is not some cheapo set... but it included zero assembly instructions.

[JohnHere]

When you connect the can tap to the can and the yellow hose to the side of the can tap--but before connecting the other end of the yellow hose to the MGS--crack open the can tap valve (CW) to see whether anything comes out the other end of the yellow hose. If not, the yellow hose is probably reversed.

[msrichmond]

When you connect the can tap to the can and the yellow hose to the side of the can tap--but before connecting the other end of the yellow hose to the MGS--crack open the can tap valve (CW) to see whether anything comes out the other end of the yellow hose. If not, the yellow hose is probably reversed.

Gas definitely comes out. And when I hook everything up, gas comes out of the MGS schrader valve when I purge the line of air. But what I never see is anything visible or cold coming out of the valve. The cans get cold. And I empty a few ounces from a can, maybe 4 of 12. I never see anything liquid in the sight glass.

In my latest round, with the engine off, I tried opening both red and blue sides and got 100 PSI on both. Then I closed the red side on the MGS and tried running the car. At most I had 8 oz of refrigerant in, maybe as little as 4 oz. I tried using warm water to get more in. The trinary switch never closes, despite the 100 PSI reading on both sides. I can manually engage the compressor and it clicks but makes no difference.

It is really hard for me to believe that a genuine Sanden compressor that cost close to $300 could be defective right out of the box. The evaporator is a well-known brand and the condenser, while cheap and Chinese, has no moving parts.

With nothing better to do I pulled out the expansion valve and put it in the freezer along with the new one from AutoZone. Both seem to work (I can see the plunger withdraw when really cold). So I decided to put the original one back in; I'm partly there. One thing I did notice was a torn #8 O-ring on the expansion valve connection to the evaporator. So that work is not wasted.

We're headed into the peak of summer here in Portland. No shop is going to want to screw around with some old car and a rookie installer. So I think I just have to wait until the fall and try again with a pro. Very discouraging.

If I were not so naturally cautious, I would turn the damn cans upside down and with the engine off, get some actual ounces of refrigerant in liquid form, wait a while until it could turn to gas and then try it again. But for the life of me I can not figure out what the hell is going on.

[JohnHere]

Your pictured can tap already has a 1/2" ACME fitting, so you don't need to use the adapter, which converts a 1/4" flare fitting to a 1/2" ACME fitting. If your yellow hose has a knurled 1/2" ACME fitting on one end, then it should screw right onto your can tap.

Don't worry about the Schrader depressor pin inside the yellow hose. The hose will still work and flow refrigerant whether or not there's a Schrader valve present.

You probably won't see any refrigerant flowing in the sight glass because you're correctly charging refrigerant vapor, not liquid, into the low side. Charging liquid into a system can be done but is not recommended for safety reasons, especially for a beginner.

If you can't get your setup to work for whatever reason, suggest taking your car to a pro A/C shop that will evacuate and charge it for you for a reasonable fee.

[tbirdtbird]

Agree