Dash Air

The device that runs every 15 seconds or so might be a small vacuum motor (about the size of a small fish tank pump) that provides a vacuum for the comfort controls. That would run if you turned on the comfort system on the dash. If it's turning off/on too often, than you have a vacuum leak and it's having trouble keeping one of the air control doors open or closed. Check those small black hoses under the dash and out under the hood for a leak. Most auto parts places carry that hose.

As far as the AC system, very few try to work on it themselves as it's big, complex, and difficult to work on without proper tools and equipment. Especially if you have a diesel. Be sure to check RVServiceReviews dot com for your area before letting someone work on it though. You might consider finding a mobile RV service in your area and see if they have HVAC training.

Good travels!

It's not Freon but 134a you can but a recharge kit at any auto parts store. Usually you buy the first can with the charger head for a little more money then additional cans if need are less. I've done it to mine and 2 years later it's still good. A friend has also done his with good results. Class A with diesels take a little more 134a as the compressor is in the back on the engine and all the piping to get it to the front. Usually there is gauge on the charging head to tell you when you are full. Just make sure you get the charging head that takes the screws on bottles.
Try it what have you got to loose if it doesn't work you will have to take to a A/C repair anyway.

Jim@HiTek wrote:
The device that runs every 15 seconds or so might be a small vacuum motor (about the size of a small fish tank pump) that provides a vacuum for the comfort controls. That would run if you turned on the comfort system on the dash. If it's turning off/on too often, than you have a vacuum leak and it's having trouble keeping one of the air control doors open or closed. Check those small black hoses under the dash and out under the hood for a leak. Most auto parts places carry that hose.

As far as the AC system, very few try to work on it themselves as it's big, complex, and difficult to work on without proper tools and equipment. Especially if you have a diesel. Be sure to check RVServiceReviews dot com for your area before letting someone work on it though. You might consider finding a mobile RV service in your area and see if they have HVAC training.

Good travels!

Thanks for the reply. I tried the AC with the engine off and the box under the dash did not cycle on and off. Could it still be a vacuum leak?

What's difficult for some is simple for others. If your condensor is in the front with it's own 12V fan, that could be what you are hearing and it's cycling because of not enough freon...R-12, R-13B1, R-22, R-502, and R-503 are all freons.

Buy a 134 recharge kit with a gauge...WalMart $20. Hook it to the low pressure port at the compressor...the only one it will fit on. If it's not in the green while running, then add 134 until in the green...should not take more than one can.

want-a-be wrote:

Jim@HiTek wrote:
The device that runs every 15 seconds or so might be a small vacuum motor (about the size of a small fish tank pump) that provides a vacuum for the comfort controls. That would run if you turned on the comfort system on the dash. If it's turning off/on too often, than you have a vacuum leak and it's having trouble keeping one of the air control doors open or closed. Check those small black hoses under the dash and out under the hood for a leak. Most auto parts places carry that hose.

As far as the AC system, very few try to work on it themselves as it's big, complex, and difficult to work on without proper tools and equipment. Especially if you have a diesel. Be sure to check RVServiceReviews dot com for your area before letting someone work on it though. You might consider finding a mobile RV service in your area and see if they have HVAC training.

Good travels!

Thanks for the reply. I tried the AC with the engine off and the box under the dash did not cycle on and off. Could it still be a vacuum leak?

I've not enough info to say whether or not the noise you're hearing is that vacuum pump or not. Usually, that pump doesn't care whether the heat is on or if the AC is on. It's the device that causes the air to be exhausted from the upper vents onto your chest, or the lower vents onto your feet, or to the defrost vents. I just checked mine without the engine running, and my little vacuum pump didn't run. It defaulted to blowing air through the defrost vents, like all auto air systems do if they lose vacuum to the air vents. If the engine is started, then that pump comes on and runs 15 seconds or so, switches to the air vent as set by the control, then shuts off. And I can seldom hear it after that due to road noise.

However, that only addresses the vacuum pump noise I think you are hearing. If you have cold air coming out of any vents with the engine running, especially the defrost vents,(be sure to check the airflow under the dash, in front of the dash, and the defrost vents on the dash), then it's probably a vacuum leak issue having to do with that little vacuum pump. If no cold air anywhere, you'll probably have to dig into the AC system.

But I don't think the vacuum pump running every few seconds is normal so that would probably need to be fixed too.

Ivylog wrote:
What's difficult for some is simple for others. If your condensor is in the front with it's own 12V fan, that could be what you are hearing and it's cycling because of not enough freon...R-12, R-13B1, R-22, R-502, and R-503 are all freons.

Actually "freon" is not a chemical description. Freon is a DuPont trade mark.
The term freon has been so misused by the public and uneducated technicians for so long that very few actually know where the work came from.

Richard

Be very careful trying to recharge this system yourself. This is a Nippon-Denzo system and only takes 2.1 lbs of refrigerant (R134 Freon with DYE), unlike the Evans Tempcon systems that use considerably more. If you overcharge the system the compressor will lock up and damage the serpentine belt while driving down the road. Then your in big trouble. It's best to let a professional A/C shop with the correct equipment evacuate and recharge the system with the correct amount.

You have to charge the refrigerant with the motor running. The AC compressor has to run to make the pressure correct on the gauge. Go slow, follow the directions on the 134a charge kit.
put it on max cool and the fan on high.