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Discussion Starter · #1 ·
I'm fairly new at this, I just came in from the shop where I was finishing up installing an underdash aftermarket AC system. (used) Its a GM A6 compressor with a Mark 4 evaporator and a new receiver/dryer.

I plumbed it last week and drew it down to -28 in of mercury and it held it for a week. It won't take the R134a. The compressor clutch is engaging and disengaging as it should from the switch on the evaporator. Right now it is showing +35 on the low side. I don't have a high side reading at the moment. I came in in frustration.

Any suggestions?
 

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I'm fairly new at this, I just came in from the shop where I was finishing up installing an underdash aftermarket AC system. (used) Its a GM A6 compressor with a Mark 4 evaporator and a new receiver/dryer.

I plumbed it last week and drew it down to -28 in of mercury and it held it for a week. It won't take the R134a. The compressor clutch is engaging and disengaging as it should from the switch on the evaporator. Right now it is showing +35 on the low side. I don't have a high side reading at the moment. I came in in frustration.

Any suggestions?
I am confused, if it is showing 35 PSI on the low side, something has to be in the system to give you the reading of 35 PSI.

has it taken any cans of Freon at all?
how many cans of Freon or OZ does your instructions call for?

I am bye no means a expert at A/C, but i just spent a week dialing in my new Vintage A/C Gen 4 system with some help of bowtie-trifive members, and needles to say i have learned allot about the new R134A.

The first thing is the R134a is very sensitive to heat and pressure unlike the old R12 that is way more forgiving.

The second thing is if you plan on charging up your new system do your self a favor and purchase the gauges, i just purchased a set of gauges and a evacuation pump form Harbor Freight on sale for 155 dollars and saved almost a 100.

The third thing i learned is just because the instructions say you need 28.8 OZ's does not make it so, i charged up my system 2 times with the recommended OZ's and every time the system was over charged and the pump would just kick in and out because the pressure was threw the roof.

The third time was the charm, even though the system calls for 28.8 OZ's i actually only ended up installing 24 OZ's and just a kiss from the third can, the pump does not cycle on & off anymore all crazzy like it was, and my temp's are 41-43*'s coming out of the center vents, and the A/C pump is staying nice and cool even after running it on the freeway for 40 miles with cold A/C blowing in my face. The trick is to charge the system monitoring your your High & Low side of the gauges at the same time to make sure you are not over charging the system and sending the PSI threw the roof, and give it 5 to 6 minutes to equalize before you add even more Freon

here is a link of the the hell i went threw for over a week trying to dial my system in http://www.trifive.com/forums/showthread.php?t=108780

or if you are not as stubborn and bull headed as i am, take it into a A/C shop and let them deal with it.....:sign0020:

Rick
 

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This is a very basic install procedure.

You will need a set of guages to the low & high side.

I normally have the system hooked up after its held vacum to a charging bottle.

Turn the A/C system on with the fan on low in the cabin, I usually have a thermometer in that vent also.

Allow the refrigerant to enter the low side, keeping an eye on the guages, just make sure when the compressor cycles it doesnt draw the low side into vacum.
 

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Discussion Starter · #4 · (Edited)
Thanks guys, I have a gauge set and a vacuum pump. I replaced the compressor on our 97 jeep and evacuated the system and recharged it without any problems using the same setup.

As I said earlier, I evauated the system to -28 inches of mercury and it held there for a week while i was out of town, so I don't have any leaks.

The internet told me the A6 compressor needs 11oz of oil in it which I added by using 8oz of pour in and a 3 oz can of draw in oil. (Peg46 oil)

When I hooked the first can of R134 it seemed to take a little bit and the low side needle climbed slowly to 35. (I have the high side shut off for charging)

There everything came to a standstill. It doesn;t seem to want to draw any more. The evaporator is blowing warm and there is at least 3/4 in the 134 can.

The first thought that comes to my mind.. Is there is something wrong with the compressor, and it is not compressing?

As I said earler, the compressor clutch seems to be working as it should.

Thanks again
 

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I`m wondering if the can is only empty, have you tried turning it upside down. Can you see anything through the manifold eye glass.
 

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Discussion Starter · #6 ·
I`m wondering if the can is only empty, have you tried turning it upside down. Can you see anything through the manifold eye glass.
As I said earlier, The can is about 3/4 full from the weight and slosh. nothing is moving in the sight glass.
 

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I sometimes have to heat the can to get the refrigerant to transfer. But generally not when getting started. To heat it, I just fill a pan with hot water and stick the can in it.

Another thing you can do is turn the can over. This puts liquid refrigerant into the system. But be VERY careful when doing this. If liquid enters the compressor inlet, you'll damage the compressor. It's a little safer to do this when there's an accumulator in the suction line, like on many 70s-90s GMs. But even with the accumulator, you can't just turn the can over and let it rip - you just put a little in and let it turn to gas before repeating.

You ought to be able to get 3/4 of a can or so in there without ever turning the compressor on. In fact the compressor isn't going to turn on if you have a low pressure switch until there's at least some pressure.

With gauges, you'll be able to see high side pressure. You should have a little bit even early on if the compressor is on and working.
 

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When I hooked the first can of R134 it seemed to take a little bit and the low side needle climbed slowly to 35. (I have the high side shut off for charging)
Is this a new evaporator or has it been sitting for a while? The expansion valve could be stuck, if it has one.
Doesn't the high side gauge show pressure, even if the gauge valve is shut off. If you have a valve near the quick disconnect, open it. When you put the first can in, it should show the same "can" pressure on both gauges. Some place above the binary switch low pressure (30 psi.). With the compressor running, the low side goes down and the high side goes up.

Is it plumbed correctly, dryer in the right direction? ..... http://www.vintageair.com/DownloadsSection/MiscDocuments/ACBASICS(92806)-Inet.pdf
 

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Discussion Starter · #9 · (Edited)
Is this a new evaporator or has it been sitting for a while? The expansion valve could be stuck, if it has one.
Doesn't the high side gauge show pressure, even if the gauge valve is shut off. If you have a valve near the quick disconnect, open it. When you put the first can in, it should show the same "can" pressure on both gauges. Some place above the binary switch low pressure (30 psi.). With the compressor running, the low side goes down and the high side goes up.

Is it plumbed correctly, dryer in the right direction? ..... http://www.vintageair.com/DownloadsSection/MiscDocuments/ACBASICS(92806)-Inet.pdf
Im going to go out and look it over again in the light of day after thinking on it overnight

the IN side of the dryer is facing the condenser just like the old one I removed.
 

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Discussion Starter · #10 ·
Im beginning to think there is something wrong with the yellow hose (blocked or something) on this fine harbor freight mainfold.

I went out and checked things this morning and the gauges are back to -28 in of mercury and the can is still pretty much full. Im going to go get a new can tap and hose and see if that makes any difference.
 

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It sounds to me like you are trying to put it in the high side. You must put it in the low side. :anim_25: bowtie-trifive :gba:
 

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Check to see that you have your hoses on the gauges the right way. There are schraeder valve depressors inside the screw on hose fittings. That's the side you should screw on to your AC system access ports Suction and Liquid line.

Yes...refrigerant cycles as a high pressure / high temperature gas from the compressor...travels to the condenser...after the condenser, the refrigerant is a high pressure / low temperature liquid...travels to the metering device (capillary tube or expansion valve) the metering device "sprays" liquid refrigerant into the evaporator where it absorbs heat and turns into a low pressure / low temperature vapor on its way to the compressor for compressing...repeat...
Savvy? At no time do you want liquid refrigerant in your compressor...liquids cannot be compressed. That's why you need thermometers and gauges to charge your system. :)
 

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Discussion Starter · #13 ·
Thanks for all the imput. I have been laid low by some kind of cold bug the last couple days so I havn't gotten anything done on it.

The compressor was originally R12 so the fittings are both the same.

I put adapters on the fittings but they are seperate. They could be attached either way.

I have the low side connect to the opening on the right side rear of the A6 compressor as you look at it standing in front of the car looking down. (Closest to the center of the engine) This is the large hose that comes out of the evaporator.

Tomorrow I am going to buy a seperate can tap and hose and see if it will take the 134 using that setup.
 

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Thanks for all the imput. I have been laid low by some kind of cold bug the last couple days so I havn't gotten anything done on it.

The compressor was originally R12 so the fittings are both the same.

I put adapters on the fittings but they are seperate. They could be attached either way.

I have the low side connect to the opening on the right side rear of the A6 compressor as you look at it standing in front of the car looking down. (Closest to the center of the engine) This is the large hose that comes out of the evaporator.

Tomorrow I am going to buy a seperate can tap and hose and see if it will take the 134 using that setup.
Were are you finding your can tap and adapter to screw into the yellow hose, Harbor Freight and O'reilys did not have the adapter, but lucky for me the plastic California adapter worked, but i would still like to purchase the correct one...

Thanks
Rick
 

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Discussion Starter · #15 ·

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Pistoncan, I have been reading your thread about your problem. You say you have your yellow hose hooked up on the low side and can't get the system to charge. I just checked my r134 gauge set. Red is high pressure, blue is low pressure and yellow is used to connect the can to the gauge manifold. Since there is no schraeder valve at the can opener end, there is no tip. Check both ends of your yellow hose for a tip to open the valve. If there is no tip, swap the blue and yellow hoses.
You could be using the wrong hose to charge the system.


Billy
 

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Discussion Starter · #17 ·
Pistoncan, I have been reading your thread about your problem. You say you have your yellow hose hooked up on the low side and can't get the system to charge. I just checked my r134 gauge set. Red is high pressure, blue is low pressure and yellow is used to connect the can to the gauge manifold. Since there is no schraeder valve at the can opener end, there is no tip. Check both ends of your yellow hose for a tip to open the valve. If there is no tip, swap the blue and yellow hoses.
You could be using the wrong hose to charge the system.


Billy
Billy, Maybe i didn't explain it correctly. Im running the yellow hose up through the manifold and down the blue hose to the low pressure connection. The point I was trying to make was that I had the red (high side) shut down. and was only feeding freon through the yellow hose to the low side.

I found the can tap seems to be plugged. I took it back to NAPA and exhanged it for a new one I will try it tomorrow.
 

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Im running the yellow hose up through the manifold and down the blue hose to the low pressure connection. The point I was trying to make was that I had the red (high side) shut down. and was only feeding freon through the yellow hose to the low side.
And that is the correct way to do it in case anyone wondered.
 

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Discussion Starter · #20 · (Edited)
COLD AIR

We have cold air. The can tap was defective, Although the replacement they gave me isn't much better, but it does work.

I found I had two problems at the same time. which as you all know, makes it really difficult to troubleshoot.

The second problem was a defective (or I bent the schrader valve installing it) adapter to convert the fittings from R12 to R134a. I switched it out with another fitting I had and the compressor took a charge. (1 can) and is blowing very cold.

I am concerned in that I don't understand why its blowing so cold with less than two cans of R134 in the system.

I don't like not understanding whats going on.

As far as I can tell. The compressor was empty of oil and I put 8 oz of pour in peg 46 oil. plus a 3 oz can of draw in Peg 46 oil for a total of 11 oz of oil, which is (from what I can glean from the internet) how much oil the A6 compressor needs.

I hope I did not get too much oil in it but I don't know how to tell.
 
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