Ac issues

[5spd540]

I just put in a ACsystem vac it down no leaks put the pag oil like required then tried to gas it could not get the low side to come up? Anyone have any ideas what wrong. It was 95 here as I was trying to has it.
190309190310190311190312190313190309[ATTACH=CONFIG]190310

[5spd540]

I checked to make sure my capaliary tube was clamped in correct spot and it was.

[grease]

I’m assuming the evaporator fan was on high. I’ve had to spray water on the condenser before to help bring down pressures where I could get a full charge.

[dhutton]

Bump up the rpms to 2000 and place the can of refrigerant in water to keep it from getting too cold. Don’t completely submerse it though. Always works for me. Placing a box fan blowing on the evaporator can help too.

Don

[5spd540]

I had the 30 pound tank in water and a fan blowing so that’s not my issue. I bumped the RPM up to 1800ish and no change. I have .3 mine gas in it that it should have but I back down the gas and does the same thing. I can’t get the low side to come up.

[5spd540]

I am being told you can’t run the unit on max air it will freeze up. It’s the way the unit is built now.

[dhutton]

I am being told you can’t run the unit on max air it will freeze up. It’s the way the unit is built now.
What unit is that?

[dontlifttoshift]

There is a dial on the capillary tube it may be part of your control panel. Set it so the compressor cycles off at 38-40 degrees based on center vent temperature.

[5spd540]

There is a dial on the capillary tube it may be part of your control panel. Set it so the compressor cycles off at 38-40 degrees based on center vent temperature.
My expansion valve is not adjustable. The company I bought it from sucks and they won’t call me back. I have called 4 times and they tell me a tech will call back when they get a chance.

[dontlifttoshift]

I am not talking about the expansion valve. You mentioned the capillary tube in an earlier post, I assumed that meant you had a thermostat with a tube inserted into the unit.

https://static1.pt-content.com/images/pt/2021/07/11092VUT__189121564759386-1.jpg?c=2

Adjusting this controls when the compressor cycles. If it is set too cold, the unit freezes up.

[5spd540]

Nothing I can do with it will keep it from freezing up other than turn up the temp on the controls in the car.

[dontlifttoshift]

Right, that's what I am saying. If the manufacturer wasn't a secret, I might be more help.

This is why Vintage Air uses a thermistor in the case on the GENIV units. That tells the ECU what the temp is, cycling the compressor accordingly so it doesn't freeze up. On the GenII units I have had to hide the thermostat so the customer would quit setting it on kill and freezing the unit.

[5spd540]

Right, that's what I am saying. If the manufacturer wasn't a secret, I might be more help.

This is why Vintage Air uses a thermistor in the case on the GENIV units. That tells the ECU what the temp is, cycling the compressor accordingly so it doesn't freeze up. On the GenII units I have had to hide the thermostat so the customer would quit setting it on kill and freezing the unit.
It’s a nostalgic air

- - - Updated - - -


Right, that's what I am saying. If the manufacturer wasn't a secret, I might be more help.

This is why Vintage Air uses a thermistor in the case on the GENIV units. That tells the ECU what the temp is, cycling the compressor accordingly so it doesn't freeze up. On the GenII units I have had to hide the thermostat so the customer would quit setting it on kill and freezing the unit.
It’s a nostalgic air

[dontlifttoshift]

Yeah, this is the thing I am talking about.


If you are using aftermarket controls they can be mounted in many different
locations, arrangements, and distance from the unit. The important step is to
insert the silver probe on the thermostat into the evaporator coil. This probe will
be inserted into the evaporator coil. The probe MUST go into the coil at least 1.5
to 2 inches.
It does not matter where it enters the fins on the evaporator, it is only important
that it is inserted. There will be a 1/2” round white sticker with a hole under it to
designate where the probe should be inserted into the evaporator.

Turning the temperature up to keep from freezing the unit is exactly how it is supposed to work.

How much R134 did you get into the system?

[5spd540]

1.7 pounds. It’s not weird that the low side is so low?

[dontlifttoshift]

Not to me......It is the suction side. If it wasn't making cold air, I would be alot more concerned. High side is higher than I would prefer but if it is holding there I wouldn't worry about it.

[5spd540]

I just have never seen a system have so low pressure on the low side.

[Chevy Kid]

I just have never seen a system have so low pressure on the low side.


We see that regularly with VA. Not to worry. I used to have a Lexus tech service my VA installs and he said a system can’t possibly work with that low a pressure on the low side. But it does!

[Twentyover]

Some aftermarket manufacturers intentionally run low suction pressures to address the use of a smaller evap. Refrigerants have a steep boiling point vs pressure curvein thi region, so a few psi suction pressure reduction makes a large change in evaporator cooling. Low suction pressure evaps do run a higher risk of evap freeze-up

OEM's address this by using larger evaps and higher suction pressures.

[5spd540]

Some aftermarket manufacturers intentionally run low suction pressures to address the use of a smaller evap. Refrigerants have a steep boiling point vs pressure curvein thi region, so a few psi suction pressure reduction makes a large change in evaporator cooling. Low suction pressure evaps do run a higher risk of evap freeze-up

OEM's address this by using larger evaps and higher suction pressures.
So my question is how do you make it cool and not freeze up

[Twentyover]

So my question is how do you make it cool and not freeze up

You depend on the manufacturer to have done his homework, correctly locating the thermistor and setting the TXV superheat. It is my OPINION that some manufacturer's may run on hope that the A/C doesn't operate long enough to freeze the evap.

I also do not accept that the expansion valve is not adjustable. All valves that I have seen are assemblies that have superheat adjustment. Most of the OEMs use block valves, where the adjustment is an external hex or torks driven bolt like head opposite the power head (the round part on one end of the valve) - Many aftermarket use an internally adjustable TXV- the variants I have seen use a hex key adjustment in the inlet port of the valve.

That said, superheat adjustment is a touchy adjustment. Never seen how they adjust valves on a production basis- when we did experimental valve settings we would set the valve up in a superheat test machine, measure, adjust (OEM style block valve) or remove the feed line, make adjustment (aftermarket valve), test, iterating until we had the superheat value we thought we were looking for.

A superheat test machine is not particularly complex, a guy could make one in his garage. The issue is, you only know in general terms what the result will be. Inadequate superheat and you'll slug liquid refrigerant back to you compressor, and the results of that are usually very unhappy.190438190439

I do not recommend screwin' around with superheat. If you do, you didn't hear about it from me