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Need to Check Charge on OTR and Cruise Air Units
89 Marathon… only one of the 3 cruise air blows cold. I get they are split systems, will be calling my HVAC person, I am assuming I need to remove the front bumper so they can access the compressors to check the R-22 Charge???? Is this just the 2 Large bolts? and will it literally,, fall off? or is it hinged some how?
Now on the OTR, it also doesn’t blow too cold, so suspect R-12?? Don’t know if it was ever converted to R-134A…. so without knowing, do I have my shop charge wtih R-12? Kinda in a dilema here….
Will any standard HVAC person be able to service these? they seem pretty straight forward from what I can see, just a simple split unit running R-22 with basic rotary controls…
The coach OTR maybe another Story….. but doesn’t really get cold…. Need to fire it to see if compressor kicks on… should I make the same assumption as a car or truck, not enough coolant, the AC unit will not fire the compressor risking damage to system? Seems logical it would be the same…
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1 Reply
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Ken,
You are correct in what Freon is used in each unit. CruiseAirs are easily serviced by an AC technician. If the issue is low refrigerant the bumper hinges down and you can access the valves for charging. If the problem is associated with a bad compressor or condenser fan I have found breaking the refrigerant connections is easy and disconnecting the 120 volt wires equally easy, and once you remove all the screws through the plywood base you can pull the whole condensing unit and service it, or replace it with a rebuilt condensing unit. I have done both, having the unit recharged, and pulling a unit and replacing it. The only thing an AC tech needs to understand is they are extremely sensitive to the amount of charge.
The amount of charge varies slightly because of the distance from the condenser to the evaporator. The best way is to use an IR gun to look for either the greatest temperature spread between the supply and return air (at least 15 degrees, with 21 degrees being really good), or the coldest temp on the suction line. Obviously the system pressures need to be according to the charts adjusted for ambient temp, but fine tuning is best done using the IR gun. When the charge is correct the sight glass will show slight bubble activity as opposed to flowing clear or a foamy appearance.
The OTR system is a straight forward service also. If you find a company that services truck refrigeration units they have all the skills required to service the OTR system. Don’t forget Prevost is a good place to get service. Generally speaking system pressures are going to be “by the book” and you can verify that with an IR gun on the temperature spread between supply and return air. When the charge is correct and the temps have stabilized the float ball in the receiver lower sight glass will be in the center.
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