Dash Air Recharge

[Dick Simonis]

All of a sudden my dash air stopped blowing cold.  Like a fool I didn't have it checked while I was at BCS for service and suspect I am low on freon.  In a bit I'll fire it up and make sure the compressor is running but, assuming it's OK, I will run into town and pick up a recharge kit.  My question is how many bottles would I need to fill it back up?

Thanks for any insight.

Dick

[David T. Richelderfer]

Dick - Have you found the valve where the refrigerant is introduced into the dash air conditioner system?  I have not looked yet but plan on soon doing what you're doing.  I know many messages here say it's over the generator between the dash and front end on my year coach.

Don't I remember that Bill Sprague wrote about how much refrigerant these systems have?

[Doug Allman]

David, we did find the low port right where you noted it would be. I am picking up new hose with high port this afternoon as when someone charged system before they evidently changed out a hose  that did not have a port on it.

[David T. Richelderfer]

I know there is a port because the sales lot had charged the dash air just before we purchased the coach four years ago.  I just do not know where it is yet.  I didn't think to ask where the port is located.  I had enough going on with the "new owner's school" that morning.

[Dick Simonis]

Well the problem isn't as simple as I had hoped.  It was easy to find the ports as they are right at the compressor but the compressor clutch isn't engaging.  The AC light is on suggesting power is being supplied but no mas.  I didn't find any relay or CB for the compressor but there is a connection on TB2 for the clutch but I haven't yet figured out if that is power supply to the AC control panel or power from the panel to the clutch.  There isn't any breaker in the DC power panel for the compressor and my wiring diagram is for a 2003 Marquis which is different then mine.

Time to dig deeper but if anyone has any insight that would narrow the search suggestions would be appreciated.

[Larry Moore]

When the system is very low on Freon,  the low pressure switch will keep the compressor from starting.  Charging the system should eventually trip the low pressure switch and then pressure readings can be taken.   

[Dick Simonis]

Thanks Larry that makes sense.  So as one puts in freon with the system operating eventually the compressor kicks on??

[Frank Bergamo]

Dick, the clutch not engaging would suggest that the freon is low, meaning that there is a leak in your system. Not enough pressure to engage clutch. A good set of gauges to monitor low and high side pressures will lead you in right direction. When recharging system, put dye in system to locate leak easier. Most motorhomes need recharging yearly. Hope this helps.

[Edward Buker]

Dick,

As long as you have some pressure then you can add slowly to the low side with the can in the upright position until the compressor kicks on. You should see the pressure slowly rise on the gauge. If the pressure is above, or rises above approximately 30 lbs while adding R134A and the compressor is not on it is likely that you have some electrical issue that will have to be sorted out.

If you are using a standard set of gauges, purge the yellow hose at the gauge by loosening the coupling while the can is upside down, and the can valve slightly open until you see 134A vapor emerge and then tighten the hose fitting. That purges air so that it is not pushed into the RV system. As far as the shorter hose recharge kits, the short hose is not much to worry about air wise. Try and get one with numbers on the gauge. If your compressor is not running due to low pressure I would have on hand 36 to 48 oz or 3-4 of the standard size 12oz cans.

This article is a good overview.

http://www.rvtechmag.com/tech/51_r134.php

The fully charged pressure with low and high sides equalized (1 hour after system is turned off or next day is better to get the temperatures of the system to a common ambient temp) is in this article. Fully charged is the pressure in the table for your current ambient as measured at the condenser face. Hope this helps.

Later Ed

[LaMonte Monnell]

I just had my dash air system completely replaced with all new parts in December at Ringpower CAT in Brooksville Florida and had cold air for two weeks. Hasn't been cold since.

I just spoke to the service manager there in July and he said that they could look for a leak by the hourly labor rate.....I don't think that's going to happen any time soon. I will buy my own sniffer on Amazon and accomplish the same thing for nothing.

About 3-4 12oz cans should be the right amount to service it.

[Dick Simonis]

OK, ran into town and bought a fancy recharge pack plus on extra bottle.  Hooked it up and the pressure on the L side indicates 100 psi so that isn't doing the trick.  Now it back to finding a way to get the compressor to run but need to find where the power comes from.  There is a single wire going into the clutch which a figure must be the +12V but no obvious connector.  Guess I could cut the wire and jumper it to a 12V source and see if the clutch engages.  There must be a fuse or someplace but there isn't anything obvious.  Do these coaches have fuses in some hidden location??

3:15 PM, to close to cocktail time to work any longer so it time to mull it over.

[Tom and Pam Brown]

Your magnum chassis manual has the amount of freon needed to refill.  Check the fittings on the compressor for oily substance.  Tighten those fittings often as they are aluminum.  If the hoses leak up front or at the compressor it should be obvious. 

[Edward Buker]

Dick,

That is a +12V wire to turn the clutch on. There is a pressure switch and probably a relay that controls the clutch. I would check the labeling in the front electrical bay and see if there is a breaker labeled air cond. If you manually fire up the clutch with the engine running, do not do it for longer then is needed to test it. If the condenser fans up front are not on the pressure will be very high. Those fans cooling the condenser keep the pressure under control. Your 100lbs would be a correct equalized charge pressure level for an 88 degree ambient. This does not have to be exact but close is good..

Later Ed

[Gerald Farris]

Dick,
There are two common locations where the 12 volt supply to the compressor are commonly lost. The first and most common one is the trinary switch that is located in the high side, usually near the dryer. The other location is the compressor control switch that is located in the master HVAC control panel in your dash.

Gerald   

[Edward Buker]

Dick,

If the trinary switch Gerald pointed you to is bad, that is usually replaceable with pressure in the system. It should have a schrader valve in the seat. It will leak some while the switch is depressing the valve but should stop at some point while unscrewing. I have only replaced two of these in different vehicles and both were schrader valved. Would hope yours is similar.

Later Ed