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where's the ac-heat switch located
January 18, 2011
10:59 am
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Steve Pooler
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I posted my last post yesterday from my phone so it may not read so well...I'll try to clarify...

  • If the reversing valve coil gets no voltage the valve will obviously not switch over...Thus no heat & the system will continue to cool...This is evidenced by a warm seawater coil....This is likely a thermostat problem.
  • If the reversing valve does have voltage but you have no heat...First feel that seawater coil...If it is no longer warm the valve has switched but you may not have enough freon to heat well...
  • If it is still warm, meaning the unit is still cooling, then it can be a bad coil, or a stuck valve...Remove the coil (one nut) and see if it will grab a screwdriver magnetically (do not leave coil off valve long or it will overheat) if it grabs a screwdriver then the coil is good, and the valve is stuck.

If you find the valve is stuck...What I do is turn off the seawater pump breaker or disconnect it's fuse/wires in the pump relay to disable it...This will allow you to run the head pressure up much higher than normal (it's head pressure thru those little tubes on the valve that help it switch)

Then with the nut removed from the reversing valve coil and the unit running in heat mode (coil has power) I slide the coil on & off of it's post...

You will hear the compressor loading up as the head pressure rises...Try to slide the coil on just before the compressor shuts off on the high pressure switch...If the compressor shuts off that ok...The pressure switch will reset itself & it will restart (unless it trips it's breaker) just catch it again on the next go round...

Of course refrigerant gauges & knowing that the switch cuts out at 425psi would help with this but it can be done without...

If you get it to free up you will know it by the large whoosh noise it will make, along with a compressor load sound change....I would continue to cycle it manually like this several times to be sure it gets lubricated and that it will switch later when you re-connect the pump...

To me...Hitting a reversing valve is a very last resort because if it is at least cooling you have that function of the system that you could live with maybe...But if you hit the valve & dent it...It could stick halfway, and if that happens you will loose cooling too...

Reversing valves are not DIY replaceable, the part is not cheap, and the condensing unit most of the time needs to be removed to replace the valve...At the price of the overall job, and considering the overall shape & age of the unit...Sometimes it's better to look at a complete new condensing unit with a warranty...

 

Steve~

January 17, 2011
3:36 pm
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Steve Pooler
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Ok...So back to the first step...
We need to see if there is voltage to the reversing valve coil...
Or does it continue cooling (compressor running with a warm water coil) ?
The water coil should get cold if it has switched to heat but the thermostat may not be sending voltage to the coil.
If it has voltage to the coil it could be low on freon.
If it does not have voltage it's a thermostat problem.
Yes...With voltage...It could mean the valve is stuck, but you would prefer it be something other than that.

Steve~

January 17, 2011
11:36 am
jaxfishgyd
Jacksonville,Fl
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Have tried it several times...Last week it was in the 20's onboard !!

January 17, 2011
10:25 am
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Steve Pooler
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3 knob controls sometimes won't go into heat mode in the summer...

The T-stat has a range that it operates in, and if not cold enough in the cabin the heat click is off the scale.

Have you tried it with a cold cabin ?...Say colder than 68 degrees (this can depend on the calibration screw on the back of the t-stat)

 

Steve~

January 17, 2011
10:15 am
jaxfishgyd
Jacksonville,Fl
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It works fine in A/C mode (noticed it didn't go to heat when I tried over the summer). I have the "old 3 knob" controls.
had it serviced over the summer but forgot to tell the tech about not going to heat (just wanted COLD)

January 17, 2011
9:54 am
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Steve Pooler
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There is no switch on the unit...There is a reversing valve, and yes sometimes it can be tapped in the right spot to free it up if it is stuck...But I never advocate doing that for DIY guys...It's way to easy to dent & render it useless if you slip & hit the wrong place...It's also expensive to replace if you do that, and I have a trick or two to try to get it to switch without hitting it...But first...

Now days with the digital controls that exercise the valve regularly...We almost never see them stick anymore anyway...

Refresh my memory on what controls & unit you have & I will try to help...

First thing to do is see if it's getting voltage...It could be a control (t-stat) problem, low on refrigerant, or water flow may be reduced...

 

Steve~

January 17, 2011
9:42 am
jaxfishgyd
Jacksonville,Fl
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seems my reverse cycle 16,000 cruiseair now doesn't want to go on the heat cycle... Know there's a switch "somewhere" on the compressor but no idea where or what it looks like..
Been told "just hit it lightly" and it'll work.... But due to the cramped area and my "big size"...
Is there a diagram I can look at?