MAINTENANCE MATTERS
Hot tips for cool AC comfort

It's easy to take air-conditioning for granted — until it stops working. Not to despair. If your coach is getting all hot and bothered, there are many things that you can do to set things right.

To begin with, know your federal and state laws about refrigerant recovery. Don't assume that complying with one set will suffice for both entities, and do not assume that a federal or state Refrigerant Recovery Certification makes someone a refrigeration expert; it only means that he or she is aware of how to handle refrigerant without releasing it into the atmosphere.

Pushing buttons
If the temps are soaring inside your coach, don't overlook the easy solution: If the driver's control/display has an "AUTO" or  "A/C" mode button, make sure that it is actually pushed in. You might be surprised at how often this tip solves a customer's problem.

Wire wise
Aside from low Freon levels, the number-one cause of A/C trouble is electrical. It doesn't take an engineer to spot blown fuses and or bad wiring: You can easily check fuses and resettable circuit breakers yourself. Make it a point to be familiar with their location, which you should be able to find by referencing your owner's manual. Carry more than a few spare fuses. Sometimes fuses will fail for no apparent reason; if you find a bad one, replace it. But if you blow it out two or three times, there may be an electrical fault.

Always use the correct ampere/size fuse. Do not ever use a fuse with a greater ampere rating than the one specified for that location. You could do severe damage to the coach or even start a fire.

Next, look for any bad wiring.  (First, remove all conductive personal jewelry as a precaution. If metal jewelry touches a live battery circuit, the circuit can short out.) The first place to look for bad wiring is at the A/C compressor.

The next place to look for bad wiring is around the engine or, on some coaches, the alternator.  This goes doubly for Delco alternator-equipped buses that show a "NO GEN" telltale. In this case, check all the wires at the alternator.

Be sure you know where a loose wire came from before you hook it up. Do not guess. Turn to a mechanic if you're not sure. There are often loose-ended spares and stray wires on older coaches. Some can create problems if hooked up wrong. And if you hook it up wrong, it will be even harder to figure the problem out.

Most buses require the charging system to be up and running before the A/C system will activate. Is there a malfunction of the charging system? Fix that first, and the A/C should come back.

Other issues
If it's not the wiring, consider your other options. Is the A/C compressor belt in place, moving smoothly and not squealing or smoking? Does the A/C compressor clutch cut in and out several times a minute, or perhaps not engage at all?  This could indicate improper Freon level or an inoperative condenser fan.

Condenser fans are located on the outside of the bus on the driver side on MCIs. If there are several fans, one or more should operate any time the compressor clutch is engaged. First check the main condenser motor circuit breaker(s) and try to reset (not all coaches have resettable motor circuit breakers). Next, shut everything off and pull the battery disconnect  switch; check/replace  the motor brushes as needed.

Evaporator (main) blower motors should run when the system is on. First check the main evaporator motor circuit breaker and try to reset it (not all coaches have resettable motor circuit breakers). Next, shut everything off and pull the battery disconnect switch; check/replace main blower motor brushes as needed.

Freon check
Checking the Freon level should be on your diagnostic checklist, but the exact procedure can vary according to model and year. Ask your mechanic to show you how it's done on your coach. Most mechanics will cooperate with requests like this, as long as they have the time.

Last but not least, if everything seems to be working, but the coach is still too hot, try shutting off the manual hand-operated water valves at or near the engine. Sometimes the main heater water valve can fail or stick open and work against the A/C system. Keep in mind that if these valves are closed, there will be no heat for the driver or the defroster system.

By the time you're done with all of the above procedures, you may well have your system running again, and, if not, you are going to have a better idea of what is wrong — or at least what isn't — so that repairs can be done quicker. If nothing else, you're going to sound like a pretty sharp operator when you talk to the shop service manager.

The FYI from MCI editorial staff values your feedback. Please e-mail any suggestions, comments, or ideas for future articles to fyi@mcicoach.com.