A/C quit Help!

[zman62]

We have a 42 ft Camelot. My rear A/C unit will start and you can hear the compressor kick in, it will then blow good cold air. After about 5 min it will start blowing very hot air. I have bypassed the thermostat but no change. Any ideas????

Thanks...

[observer]

If you remove the inside air filter you will see a control box that has few "phone plug" like connectors. Try removing and reinstalling those connectors. It sounds like the unit is going into a heat pump mode. One of those connectors is a sensor for the heat pump operation.

[zman62]

Quote:

Originally Posted by observer If you remove the inside air filter you will see a control box that has few "phone plug" like connectors. Try removing and reinstalling those connectors. It sounds like the unit is going into a heat pump mode. One of those connectors is a sensor for the heat pump operation.

I just tried this and unfortunately the problem is still there. It is exactly 7 minutes after start up the cold air switches to hot. You can hear it . I agree, its switching into heat mode. Any other ideas????

[itdave]

I don't know why they did it this way but the reversing valve needs to have 120 volts applied to keep the unit in cooling mode. I was having a similar problem on mine and found that there was only about 80 volts getting to the reversing solenoid. On mine the cause was a start capacitor that was partiality shorted to the case. Go on top of the coach and pull the cover off the A/C. With a meter measure the voltage at the solenoid when it switches to heat, if you see zero then something in the control circuit is probably tell it to switch to heat. If however you see some voltage but less than 120 volts look for some bad connection or a path to ground. On mine the start capacitor was leaking and providing the ground path. I replaced the capacitor and that fixed the problem.
BTW if the start capacitor is the problem try to get one from a electric motor repair shop instead of from an RV dealer. I found that the capacitor cost $10 at the motor shop and $40 at the RV dealer.

[zman62]

Quote:

Originally Posted by itdave I don't know why they did it this way but the reversing valve needs to have 120 volts applied to keep the unit in cooling mode. I was having a similar problem on mine and found that there was only about 80 volts getting to the reversing solenoid. On mine the cause was a start capacitor that was partiality shorted to the case. Go on top of the coach and pull the cover off the A/C. With a meter measure the voltage at the solenoid when it switches to heat, if you see zero then something in the control circuit is probably tell it to switch to heat. If however you see some voltage but less than 120 volts look for some bad connection or a path to ground. On mine the start capacitor was leaking and providing the ground path. I replaced the capacitor and that fixed the problem. BTW if the start capacitor is the problem try to get one from a electric motor repair shop instead of from an RV dealer. I found that the capacitor cost $10 at the motor shop and $40 at the RV dealer.

I just went up and took the cover off to check some voltages. I discovered that what I think is the capacitor was just bouncing around in there and has shorted to the casing. Few wires are burned but one of the contacts is burned off the capacitor. I am not sure how he wiring goes back having not seen how it came apart. My thought is if I buy a new capacitor i should be good to go. There is a spot where it looks like a ground wire was attatched to the casing but its gone or burned. Any help on how this goes back together would be great.

Thanks

[observer]

Zman,
If you are trying to hook up a new capacitor why not compare it to the wiring in your other roof A/C?

[itdave]

Since I started you on this path I figure I have a responsibility to help if I can. Because of some strange happening I have a 13.5 Penguin A/C Heat Pump unit sitting in my garage. So I went out and took some pictures which I hope will help. In words one tab on the start capacitor is connect with a white wire to a common ground post on the run capacitor, the center post on the start capacitor is connected to the reversing valve with a black wire and the last post has a red wire which goes to the compressor. Here are the pictures.



First picture is of the small black Start Cap showing white wire that connect to common tap on run cap, black wire that goes to reversing valve and red wire for the compressor start.

Second picture shows the small black start cap, large gray run cap and how they are connected.

Third picture is the wiring diagram

I tried to do this by linking to the pictures in Picasa but failed. I guess I need a lesson from Mama on picture sharing. Here is a link to the Picasa web album CLICK HERE

[zman62]

Quote:

Originally Posted by itdave Since I started you on this path I figure I have a responsibility to help if I can. Because of some strange happening I have a 13.5 Penguin A/C Heat Pump unit sitting in my garage. So I went out and took some pictures which I hope will help. In words one tab on the start capacitor is connect with a white wire to a common ground post on the run capacitor, the center post on the start capacitor is connected to the reversing valve with a black wire and the last post has a red wire which goes to the compressor. Here are the pictures. First picture is of the small black Start Cap showing white wire that connect to common tap on run cap, black wire that goes to reversing valve and red wire for the compressor start. Second picture shows the small black start cap, large gray run cap and how they are connected. Third picture is the wiring diagram I tried to do this by linking to the pictures in Picasa but failed. I guess I need a lesson from Mama on picture sharing. Here is a link to the Picasa web album CLICK HERE

Thanks for all your help! I finally found the start capacitor and installed it today. Tried it out and the a/c does the same thing. Cold for about 7 min then goes hot. I assume I need to check voltage at the switch solenoid?

Thanks again for all the help!

[Mr V]

Hi Everyone,

I too am having AC/Heat Pump problems, In reading this post I have tried some of the recommendations,

The Front AC was throwing heat in the cool mode,I went up on the roof and changed both front capacitors with the rear unit and the rear to the front.

Rear unit works fine as before, front still throws heat.

In playing with the thermostat I noticed that there is no heat pump setting on the menu on zone one like it used to show, zone two has a heat pump setting as always.

It is supposed to go to 95 this weekend!

Please help

[Mr V]

Thank You for all the help I am sure I would have received, turns out there was a loose wire on one of the internal contacts on the unit circuit board.

All works fine.

Hopefully it might help someone else if they experience a similar problem.

[zman62]

Ok I know its been a while. I ran out of time and had to put the coach in storage. I got it out today. I have put a new start capacitor on it and it still switches to heat pump after about 7 minutes then back to a/c after that. I have checked voltage to the reverse valve and its a constant 118v even when it reverses. Its my understanding that it should go to 0 when it reverses. My thought is that I have a bad reverse valve. Any thoughts???

[PizzaGuy]

I have a Duo therm service book. This is from the book.
C13. Reversing Valve

The reversing valve is the heart of the heat pump. It directs
refrigerant flow to the coils to achieve proper direction of
flow that allows the same system to supply heated or cooled
air to enter the inside atmosphere of the structure according
to occupants. desires.
The reversing valve.s solenoid can be energized in either
HEAT or COOL mode of operation. Most Duo-Therm Heat
Pumps have the solenoid energized in the COOL mode of
operation. The Dual (Model 39424) has the solenoid energized
in the HEAT mode of operation. See FIG. C19. The
solenoid on the reversing valve can be loose, this will cause
a humming noise during the off cycle; especially is the
blower shuts off with the compressor. Check the screw
holding the solenoid coil on the reversing valve for tightness.
One way to check the reversing valve is to feel the refrigerant
line at the top of the inside coil. In the COOL mode, this
line will be cool or cold to the touch. In the HEAT mode, this
line will be warm or hot to the touch. If you do not achieve
these results, direction of refrigerant flow is not correct.
The ohms resistance of the reversing valve solenoid coil is
approximately 465 ohms plus or minus (±) 10%. If ohms
reading is within this range, the solenoid coil is good. If
ohms reading is outside this range, replace the solenoid
coil.
On Model 39424, verify AC volts are to the solenoid coil
when in HEAT mode. If AC volts are NOT present, verify
wiring is correct, especially to the 9-pin terminal connector.
Check that the connection is completed through it. Next,
verify power module board and the relay are good. If AC
volts are present and solenoid coil is good, but refrigerant
flow is not proper, the reversing valve assembly needs to
be replaced.
On all other models verify AC volts to the solenoid coil when
in COOL mode. If AC voltage is NOT present, verify wiring
is correct, especially to the 6-pin terminal connector. Check
that the connection is completed through it. Next, verify
power module board is correct, then verify relay is correct.
If AC volts are present and solenoid coil is good, but the
refrigerant flow is not proper, the reversing valve assembly

needs to be replaced

If you remove the cover inside the coach you will see a 6 pin connector. Pin 3 (should be a yellow wire) is for the heat pump.

I will try to find the web site where i downloaded the book

Good Luck

[PizzaGuy]

go to this link Service Documents about half way down the page you will see listings for duo therm a/c with heat pump. You can download and print the file to help you troubleshoot the unit.

[zman62]

Quote:

Originally Posted by PizzaGuy go to this link Service Documents about half way down the page you will see listings for duo therm a/c with heat pump. You can download and print the file to help you troubleshoot the unit.

Thank You!!!