Air Conditioner Thermostat Codes

[stageboss]

I have a 2003 Catalina 310 with factory A/C. Lately when I turn on the A/C it runs for 5 or 10 minutes and then stops cranking out cold air although the blower is still running. The Control Pannel displays these two error codes "P5" & 'HI". I don't have the documentation for the control head so I can't look up the owner's manual as I don't know the model number. Does anyone recognize this unit, and can you tell me what the model number is? Also do you know what the fault codes refer to.

 

[Davidasailor26]

On my Dometic / Cruisair thermostat HI/PS means high pressure shutdown. See page 15 of the attached PDF.

I’ve gotten that code a few times in heat mode. Mine has never thrown it on cool. We had a tech check ours out and he just recommended making sure nothing was blocking the airflow through the flexible ductwork or at the ducts. That seems to help a little. To fix it consistently we set the fan to manual mode on at least 3 bars (out of 5). When the system is in heat mode and the fan automatically drops to lower speeds it seems to throw the code more often.

 

[WayneH]

That code appears on my dometic when the seawater strainer gets fouled. Not enough cooling water to reduce the freon head pressure. YMMV

I also get the P5 LO in the winter when the bay gets too cold.

 

[stageboss]

On my Dometic / Cruisair thermostat HI/PS means high pressure shutdown. See page 15 of the attached PDF.

I’ve gotten that code a few times in heat mode. Mine has never thrown it on cool. We had a tech check ours out and he just recommended making sure nothing was blocking the airflow through the flexible ductwork or at the ducts. That seems to help a little. To fix it consistently we set the fan to manual mode on at least 3 bars (out of 5). When the system is in heat mode and the fan automatically drops to lower speeds it seems to throw the code more often.

Thanks all for the heads up. Do any of you know the model number?

 

[Davidasailor26]

Mine is a Dometic CruisAir STQ16-410A Air Conditioner with reverse cycle, and a Dometic CruisAir QHT Q Logic controller. I presume they use the same codes on most of their similar equipment though.

 

[stageboss]

Mine is a Dometic CruisAir STQ16-410A Air Conditioner with reverse cycle, and a Dometic CruisAir QHT Q Logic controller. I presume they use the same codes on most of their similar equipment though.

You're probably right about the codes. Mine doesn't have the mode button but I will follow the trouble shooting procedures outlined in the manual you attached. Thanks again for your help.

 

[BigEasy]

I have a 2003 Catalina 310 with factory A/C. Lately when I turn on the A/C it runs for 5 or 10 minutes and then stops cranking out cold air although the blower is still running. The Control Pannel displays these two error codes "P5" & 'HI".

I have a different circuit board & controller on my Dometic heat pump; however, I have chartered boats that have a Dometic system like yours. As others have mentioned, "HI" pressure codes can indicate restrictions in the raw water strainer & lines; ensure that the thru hull fitting doesn't have a plastic bag or seaweed blocking water flow. Also , blockage in the strainer & water line to the condenser can trigger a hi pressure fault code. The strainer can become clogged with algae, especially in summer months when the air conditioner is used more frequently. Also, realize that the controller can be programmed for the fan to run in two modes: (1) fan runs continuously at varying speed & condenser turns off when temperature set point is attained and condenser turns on again when temperature rises above set point. (2) fan & condenser turn off simultaneously when temperature set point is reached & both turn on again when temperature rises above the setpoint. You can set it in either mode depending on your preference.

 

[stageboss]

I have a different circuit board & controller on my Dometic heat pump; however, I have chartered boats that have a Dometic system like yours. As others have mentioned, "HI" pressure codes can indicate restrictions in the raw water strainer & lines; ensure that the thru hull fitting doesn't have a plastic bag or seaweed blocking water flow. Also , blockage in the strainer & water line to the condenser can trigger a hi pressure fault code. The strainer can become clogged with algae, especially in summer months when the air conditioner is used more frequently. Also, realize that the controller can be programmed for the fan to run in two modes: (1) fan runs continuously at varying speed & condenser turns off when temperature set point is attained and condenser turns on again when temperature rises above set point. (2) fan & condenser turn off simultaneously when temperature set point is reached & both turn on again when temperature rises above the setpoint. You can set it in either mode depending on your preference.

Again, thanks for your input. One thing though is that I don't have a mode button on my unit so I'm not sure how to go about changing the mode other than from cool to heat. I'll get working on figuring out if there are water supply issues soon as this tropical storm were having here in So Cal passes. So far not much wind which is good.