MarineAir Won't Go to Cool Mode

[Curtis]

Our aft AC has the old mechanical three knob rotary controls. I've noticed over the past few months that the "switchover" spot has been shifting to the cooler side. (I've had to turn the knob further to get it to cool mode). Well, it has finally shifted enough so that I can't turn the knob far enough to get to cool mode.

I'm fairly sure this is just a mechanical problem with the switch because you can hear a click in the knob when it triggers the appropriate mode: Turn to the left, and it clicks to go into heat mode. Turn to the right, and it clicks to go to cool mode. Right now, I turn to the right and it turns off heat mode, but won't ever click to start the cooling cycle.

Is this control adjustible somehow? I've looked around on it and didn't seen anything obvious. The control is labeled C17-229-000, MAX. SENSOR, 0137 26, Temp 65.6C

Thanks,

Curtis

[mobetah]

Curtis,

I might just be that the knob is not tighten down on the stem ..... there are 2 (or 3) set screws on the knob after making sure that the knob is in the right location tighten down all the set screws on the knob. This happened to me not long ago!

Good Luck, Bill A.

[Curtis]

Originally Posted by mobetah

Curtis,

I might just be that the knob is not tighten down on the stem ..... there are 2 (or 3) set screws on the knob after making sure that the knob is in the right location tighten down all the set screws on the knob. This happened to me not long ago!

Good Luck, Bill A.

Thanks, Bill. I doubt that is the issue as I can turn the knob to both stops and it is operating the control because the compressor turns on or off based upon the location of the switch. The problem is that the range of operation seems off...

[sv-Mystique]

I doubt it's the switch - have the freon checked..........

[Curtis]

Originally Posted by sv-Mystique

I doubt it's the switch - have the freon checked..........

Well, it works fine in heat mode...that wouldn't happen if it was low on refrigerant. Also, the fact that his has been "shifting" over the past few months leads me to the temperature control.

[sv-Mystique]

fair enough - i didn't see where it worked in reverse mode, sorry...... Where is the thermostat?

[Curtis]

Originally Posted by sv-Mystique

fair enough - i didn't see where it worked in reverse mode, sorry...... Where is the thermostat?

I believe the temperature control IS the thermostat on this one...just a rotary knob that you turn left for hotter and right for cooler. When it works you can turn the knob and feel the clicks that would cause the compressor to start in either heat or cool mode.

[mobetah]

Curtus,

Humor me, take the knob off the stem and use pair of vice grips or pliers to turn the stem and see if the thermostat works. If it does, I'm right. If It doesn't, what have you lost? I still think you are moving the knob but not the stem (mine did exactly the same thing, would turn warmer on but not cooler. Believe me, it's worth a shot ....... that thermostat is going to be expensive from Marine Air and if it's like mine it's not going to be easy to install since the sensor is on coils.

Again Good Luck (and let me know what you figure out), Bill A.

[Curtis]

Originally Posted by mobetah

Curtus,

Humor me, take the knob off the stem and use pair of vice grips or pliers to turn the stem and see if the thermostat works. If it does, I'm right. If It doesn't, what have you lost? I still think you are moving the knob but not the stem (mine did exactly the same thing, would turn warmer on but not cooler. Believe me, it's worth a shot ....... that thermostat is going to be expensive from Marine Air and if it's like mine it's not going to be easy to install since the sensor is on coils.

Again Good Luck (and let me know what you figure out), Bill A.

Ok, Bill...I'll give it shot when I'm back aboard in a couple of days.

Believe me, I hope you're right!

c

[GordMay]

Originally Posted by mobetah

Curtus,

Humor me, take the knob off the stem and use pair of vice grips or pliers to turn the stem and see if the thermostat works...
... I still think you are moving the knob but not the stem...

A VERY common, and cheap to fix, problem with rotary knobs.
Sometimes, the knob will partly turn the stem until it reaches a switch detent.
Never overlook the obvious.