Community Forums

TQ60 · 10-04-2016, 07:51 AM

Get a manifold to be sure.

Auto zone may loan one out or buy at hf.

Often the compressor can draw down the suction side or the evaporator has a sensor that also cuts out the compressor if it gets too cold.

Review the chassis manual for additional information as well.

Could be dryer is clogged up allowing compressor to draw pressure down or could be bad switch.

DO NOT bypass the switch as it is protecting the compressor.

6 cans likely too much for front engined unit...think standard van size...but it could be close.

You may have a high pressure cut out switch as well...that would give yiu your issue.

Your next step is get a manual to review and a manifold.

It looks like it is trying to work...

leadman · 10-04-2016, 09:52 AM

Does your hose have a gauge on it? If so what does it read?

Deano56 · 10-04-2016, 07:26 PM

Quote:

Originally Posted by TQ60

Get a manifold to be sure.

Auto zone may loan one out or buy at hf.

Often the compressor can draw down the suction side or the evaporator has a sensor that also cuts out the compressor if it gets too cold.

Review the chassis manual for additional information as well.

Could be dryer is clogged up allowing compressor to draw pressure down or could be bad switch.

DO NOT bypass the switch as it is protecting the compressor.

6 cans likely too much for front engined unit...think standard van size...but it could be close.

You may have a high pressure cut out switch as well...that would give yiu your issue.

Your next step is get a manual to review and a manifold.

It looks like it is trying to work...

Chassis manual, never seen one for this, doubt I could even find one. All the info that was decaled or written where the evaporator coil box is, weathered away. There is a pressure switch in the low side line near the small canister with the sight glass on it. The wires from there run to the fans on the condensor, I should say there is a wire coming from another switch under the evap coil box. I'll take a few pics. There are no other in line switches.

Roosters 67 · 10-04-2016, 07:34 PM

If you have a sight glass, that should be on the outlet or high side of the condensor indicating an expansion valve system. I assume this was originally an R12 system? .

Is this a orifice tube system, or expansion valve system?

Deano56 · 10-04-2016, 07:41 PM

Quote:

Originally Posted by leadman

Does your hose have a gauge on it? If so what does it read?

yes, it read 25psi

TQ60 · 10-04-2016, 08:01 PM

If Chevy chassis then Haynes and Chilton may have a generic chassis manual.

If a sight glass then go old school...should be just a bit of bubbles flowing as R134 uses of about 80%

Deano56 · 10-05-2016, 06:15 AM

Quote:

Originally Posted by Roosters 67

If you have a sight glass, that should be on the outlet or high side of the condensor indicating an expansion valve system. I assume this was originally an R12 system? .

Is this a orifice tube system, or expansion valve system?

if sight glass is on high side, I messed up. An online source on how to do a change over said the opposite. Yes R12 and yes expansion valve system.

leadman · 10-05-2016, 08:06 AM

The drier that has the sight glass is on the high side, acts as a reservoir feeding the expansion valve. The low side starts in the evaporator in the cab and goes back to the compressor. The size of the hoses will help you, hi side is smaller diameter.
You don't by chance have another evaporator in the coach somewhere?
My 1988 Itasca took 42 ozs. of 134a with the original condenser.
I do agree that the sight glass in the drier should be showing bubbles when the charge is correct. Use this along with the temperature coming out of the dash vents to help determine correct charge.
#25 on the low side is a good reading but if you can get a manifold set it would be good to use it.
What temperature do you have coming out of the dash vent closest to the evaporator in the cab? This is probably on the passenger side of the dash.
Depending on ambient temperature and humidity 40 degrees would be good.

Deano56 · 10-05-2016, 10:26 AM

What do I do with the freon I put in the high side? Did it ruin the compressor? Theres no cold are coming out the vent, compressor does run long enough, just on and off quickly

Deano56 · 10-05-2016, 10:29 AM

Havent seen another evaporator, just on the passenger side firewall

Roosters 67 · 10-05-2016, 09:17 PM

Fast cycling of the compressor could either be under charge or overcharge depending on the binary safety switches used on the system. Most R12 systems with an expansion valve used a high pressure cut off switch and may likely have a low pressure cut off also for compressor protection.

Really need a manifold gauge set to get good accurate low side and high side pressures for a better diagnosis, and understanding of what is going on inside the system. You will likely need an adapter for the high side connection. High side is commonly a smaller fitting than the lowside.

Deano56 · 10-06-2016, 03:27 AM

Quote:

Originally Posted by Roosters 67

Fast cycling of the compressor could either be under charge or overcharge depending on the binary safety switches used on the system. Most R12 systems with an expansion valve used a high pressure cut off switch and may likely have a low pressure cut off also for compressor protection.

Really need a manifold gauge set to get good accurate low side and high side pressures for a better diagnosis, and understanding of what is going on inside the system. You will likely need an adapter for the high side connection. High side is commonly a smaller fitting than the lowside.

have the adapters that was the only way I could fill up the freon my neighbor has a set of gauges and he said he's going to help me on it