I recently bought a new belt for my A/C, but it makes a wierd whirring noise when it's off and when you turn it on, it quits whirring, but it doesn't put out any cool air. I have never tried the A/C before, but it looks like the clutch for the pump barely grips when its off. Any help or tips would be much appreciated!! Thanks, Andrew P.S. - It's getting hot up here!! 96 degrees yesterday!
The compressor should not turn at all when it is in the off position. It is a magnetic clutch and only turns on when ac is selected and the fan is turned on. However, there is a pressure switch in the circuit also and the clutch will not engage if it is low on freon. Best bet is to spend the money and have it checked out by professionals. Be prepared to spend some bucks getting an old AC system working.
fwiw ac info The lady I bought my 77 Mav from replaced her a/c compressor. I was over $1000.00 just for the compressor and labor a year and a half ago. JC Whitney sells complete (no freon I think) for about $1000.00. I does not look like it is vehicle specific. R, Matt
This is not true. The A/C will also work with the defroster on. It comes on to remove the moisture from the intake air so the windows dont fog up. Yes even with the heat all the way up and in winter time. That is why sometimes you see A/C compressors unpluged during winter so it does not put exessive wear on the compressor. The wurring sound that the compressor makes when not engaged is a bad compressor clutch assembly. Probably got hot at one time in its life and warped the clutch. If it engages and no cold air comes out it is probably very low on freon. An A/C system can have enugh pressure in it to engage the low switch but not enugh freon to cool the car. The clutch assembly is not hard to change, one nut or bolt and a couple of snap rings. The new clutch should come with spacer washers to gain the proper clearence for the clutch. The directions with the clutch should give you pretty streaight forward procedures for the replacement and adjustment of the clutch. After replacement you need to make the decision of retrofitting the system with R143a or charging it with R12. Good luck and I hope this info will help. Don
You really need a manifold set to figure out what wrong with the system. Of the many old AC systems I have worked on, most of the time the expansion/throttling Valve gets stuck and must be replaced as this is the part that makes the freon change states(liquid to gas) thus getting cold. But, professional equipment is needed to find out. As for the whirring, it probably is the clutch assy but, if it hasn't been used in awhile it might just have rust built up in it. or the bearing could be bad. There is a spec for how far away the clutch needs to be from the pulley (try chiltons) measure that with a feeler gauge at several different points to see if the clutch is warped. You can disassemble the clutch and clean the parts and replace the bearing if it's just rusty. I don't recommend doing that unless you have the system evacuated. 100+psi behind the seal can (sometimes) blow the clutch right off after you remove the bolt holding it on. Seen it happen.....not pretty. Better safe than stupid. If you do switch to R134a make sure you have a temp gauge as it can cause overheating. Also, you should run a R134a system at least once a week, even in the winter as it does not carry oil very well and we all know how mechanical things like oil. (plus it keeps the hoses wet on the inside and prevents some of the need for that 'It's summer and my AC is low') R134a is WAY cheaper but it has it's drawbacks.
Actually, the Maverick A/C system does NOT have a low refrigerant switch. It has a thermostatic switch mounted to the outside of the AC/heater box under the dash..it has a long probe that goes thru the box into the evaporator core. When the core gets to near freezing, it interrupts the circuit going to the clutch and shuts it off until the temp in the core rises enough to turn the switch back on. This prevents the evaporator from freezing up. Many times if the refrigerant charge is low, the evaporator will start freezing quickly, causing the clutch to cycle on and off quickly. Unlike more modern systems, the pressure inside the system is not measured directly...so if the charge gets low enough the clutch will run continuously...which is not a good idea (and why newer systems have a pressure switch. )
