Community Forums

dlaske · 03-22-2023, 09:06 PM

I have a 2004 8.1 Workhorse W22. I have been having trouble adding freon to the system. There is a small black valve above the low pressure input valve. When adding freon should this valve be turned to open? What is this black valve for? How does it work?

1972VWbus · 03-22-2023, 09:51 PM

Post up a pic of the low side valve/s in question.

As for Freon charge info:

RV APPLICATIONS

GM (Chevy) P-30, L-19, L-29, L-65 2.75 Lbs.
GM (Chevy) P-12 w/Parallel-Flow Condenser 2.0 Lbs.
Workhorse before '05 model except W-24 2.75 Lbs. (1)
Workhorse - all models with black Behr condenser and two fans 2.00 Lbs.
Workhorse W22/W24 w/Multi-flow Condenser and no fans 1.5 Lbs.
Workhorse Front Engine Diesel 1.75 Lbs.
Ford E-33 w/Serpentine Condenser 2.25 Lbs.
Ford F-53 w/Fin & Tube Condenser 2.75 Lbs.
Ford F-53 w/Silver Multi-flow Condenser(starting with MY2012) 1.75 Lbs.
Ford V-10 Super Duty w/6mm Condenser 2.75 Lbs.
FTL Front Engine Diesel w/Parallel-Flow Condenser 1.5 Lbs.
FTL Front Engine Diesel w/remote mounted condenser and fan 2.25 Lbs.
(1) For W22 without an auxiliary condenser, charge would be 1.75 lbs and performance would be reduced.

dlaske · 03-26-2023, 07:24 PM

I took a picture of the valve. I think it is an open / close valve.

TXiceman · 03-26-2023, 07:31 PM

I would strongly suggest you take this to a professional before you are injured, or you damage the unit more than short of refrigerant. Your first mission is to find and repair the leak,

Ken

dlaske · 03-26-2023, 08:08 PM

Quote:

Originally Posted by dlaske

I took a picture of the valve. I think it is an open / close valve.

I have been to 4 different dealerships and spent over $4k and still have warm dash AC. None of the dealerships are sure how that valve above low presure valve works! I hope someone here knows!

Full-Timers · 03-26-2023, 08:18 PM

See this post. It explains it all.

https://www.irv2.com/forums/f22/dash...lp-491816.html

code2e · 03-26-2023, 09:11 PM

Quote:

Originally Posted by dlaske

I took a picture of the valve. I think it is an open / close valve.

In the earlier days of A/C, those were called service valves. Under the black screw on cap is the valve shaft with a hex. Some were 1/4" or 5/16" 6 point hex. Some were 4 sided square drive. Use either a socket or a small wrench as required. The construction of the valve is much like a outdoor faucet on your house, except it opens and closes each direction. Fully clockwise, it closes off the refrigerant line. Fully counterclockwise, it closes off the refrigerant service port. You need to connect your low side service hose first, connected to your gauge set. Then turn the service valve about a full turn clockwise. In that position both ends are open and your gauge set will read low side pressure. You can evacuate, vacuum or charge the system. Once done, turn the valve fully counterclockwise and remove your gauges. System is sealed. Always replace both caps as they are secondary seals.

Older systems that used York or Tecumseh compressors used those service valves at the compressor ports. Besides normal charging, the valves enabled removal of the compressor without losing the system charge. Helped when replacing compressor seals.

craigd853 · 03-27-2023, 05:00 AM

Quote:

Originally Posted by dlaske

I took a picture of the valve. I think it is an open / close valve.

Hello, sorry for your issues. This is called a schrader valve and yes you have to open it in order to fill the a/c system. Take the black cap off the valve and you have to turn the schrader valve clockwise to open I believe. If you have gauges on the system when you open the valve you will see the presure come up on the low side. Like others have said, best to find the leak and fix it, as with any leak over a period of time your system loses the oil that is in it for lubrication and could potentially lead to compressor failure. Good luck and I hope this helped. You can use an adjustable wrench or a scket to open valve once black cap is removed.

TXiceman · 03-27-2023, 07:29 AM

You are getting both good advice and bad advice here. The smaller cap and port is the service port and probably has a Schrader valve. The core is like the air valve on a bicycle tire/tube. The larger black cap has the service valve stem, and it will be a square drive more than likely. It might be a hex stem or a recesses allen wrench type.

The large aluminum block under the valve is the thermal expansion valve. To add refrigerant, you attach the hose to the smaller service port (a flare connection) with the refrigerant bottle attached to the other end. Open the valve on the refrigerant bottle and loosen the hose at the charging port to bleed some refrigerant and push the air out of the charging hose. Finger tighten the hose at the charging port. Be careful to not getting a freeze burn from the refrigerant. (always wear gloves and eye protection when handling refrigerant). With the vehicle running at high idle speed, and the A/C running on high fan, crack open the charging valve and let refrigerant vapor flow into the system. Close and open the charging valve on the gauge manifold observing the suction pressure on the gauge. Close the valve at the service port and close the refrigerant bottle. Slowly loosen the hose at the charging port and release the pressure (wear gloves).

From the age of the RV and the appearance of the valves, you should be using R-134a.

Since your experience is limited for refrigerant handling, I still recommend that you have this done by a licensed refrigerant technician. Any decent A/C tech should be able to perform this service. If they can't check and charge something as basic as this equipment, they need to find another line of work.

Ken