I picked up a new governor for my truck and had a question about blocking the extra ports. Truck has an AD-9 air dryer. Should the port on the governor marked EXH (exhaust?) Have a plug in it if the unload line runs to the dryer purge valve? The old governor didn't have plug in that spot, so I left it open for now. The old governor was seized and wouldn't unload the compressor so it just kept building air until the tank PRV popped at 150 psi. I'm probably going to install a reman air dryer too, once the weather gets a bit warmer. Judging by the general corrosion on it, it hasn't been serviced in awhile.
Exhaust port should always be open to atmosphere. People putting plugs in there are no end of a source of problems. A screen is a good idea if bugs may get into it. There may be applications that require some kind of line to be attached to the exhaust port but I don't know what they are.
Driers cycle on Unload pressure, that is why they tend to short cycle when the drier exhaust seals go to hell.
Ok, I just wanted to make sure. I set it up same as the old one came off the truck.
Well, I got no air at all now. Yesterday I started truck, walked off to let it air up, came back and no air. Didn't have time to deal with it so I plowed the drive with small tractor. Swapped governors this morning thinking the old one had finally given up, only to start truck up and still not be able to build air pressure. I checked the petcock on tank, absolutely no air came out. So it's not making any. Last I ran truck was 12/28. It was 40 degrees out. Yesterday was 10, today, below zero. I'm wondering if something is froze up, but I really don't know where to start looking
If you remove the governor and discharge line from the compressor, it should pump air out the discharge port. The governor tells it to stop pumping by applying air to the UNL port. So if the governor is removed it should pump. Frequently the first thing to freeze is the discharge line from compressor to wet tank. Start at the beginning and follow it out until you find the source of the malfunction.
Dryer is frozen
Likely drier as TS notes. Too much heat in compressor head for unloader seats to stick from cold.
Alright, sounds like I'll be starting with that in the morning. Supposed to be 9 below tonight with 20mph winds. I won't be tackling this tonight. Napa shows a reman AD-9 Dryer for $149. I'll probably R&R this and be done with it, I have snow to plow.
To verify you can tie the two large air lines together and see if you make air. That or remove the supply line and see whatcha got there. I’ve always carried a means to bypass the dryer in a pinch if it happens to freeze up. Don’t ask how I learned that. If it’s all stratoflex lines it’s more than like a #10 union to hook supply to discharge. The new one should have a heater in it, it’s worth the time to wire it up.
For a check first-remove the discharge hose from compressor at the AD-9 dryer supply port to make sure the compressor is operating. Re-install that hose to dryer and remove the hose from the delivery port to air tank-no air dryer is froze up.
Had one a few weeks ago, the dryer passed air but the line to the wet tank had a low spot that was full of water. They had never changed the desiccant filter in how many years?
Usually the compressor-discharge-dryer-wet tank are all in proximity. Do you have a torpedo heater and a tarp you can use to get the whole works above 32 degrees and see if that fixes it?
I appreciate all the insight and comments guys. I'm not going to tarp it this time as we are supposed to get above freezing this weekend. It can sit until then if it needs to. I'll certainly try pulling the supply line off to make sure it's getting air that far. The heater on the air dryer is plugged in, though I don't know that it has power. I'll have to check that tomorrow. I'll report back with what I find tomorrow afternoon.
I don't think the heater on the air dryer heats much more than the little purge valve itself. It is not a very powerful heater so if something in the discharge line going into the dryer is frozen solid the electric heater will not likely help.
Little heaters did barely put out enough heat to keep the exhaust system thawed, would still tend to freeze up on the road in severe cold.
As you guys said, air dryer is frozen, and so is supply line. I'm going to put a new dryer on it, but not til after I get that line thawed and drained. It's supposed to be above freezing Saturday, so I'll work on that then. Then I'll be checking tanks and everything else to make sure I got the moisture out.
A little frogging around Saturday morning found the supply line froze for about 18" back. Birken's idea of a tent and salamander heater would have been necessary if it hadn't warmed up to 50 like it did. I was able to start the truck and let it build enough pressure to blow the ice chunks out. Builds pressure and purges at 125psi like it should now. I was surprised, I called around and found that NAPA had the air dryer locally, and I was out the door for under $200 for a new unit (not a reman) with no core.