For the A/C experts...

[MikeP]

My forward ac unit is acting up. I have the FX1 controllers and the ac systems has been working fine. However, suddenly (this happened last year but I've been away from the boat since then) the control box for the bow/galley ac has no control over the compressor. Any time the circuit breaker is on, the compressor starts running but the air handlers/fans do not. There is power at the FX1 but the display no longer illuminates and the FX1 does not have any affect on the compressor. I switched FX1 boxes but no difference.

I'm assuming something has failed in the master box for the bow/galley unit in the engine room but I don't know anything about the actual circuitry in the boxes. I have replaced several triggers in the past but they control only the seawaater pump AFAIK.

It seems to me that some component has failed/shorted internally and that power/signal that should be routed to the FX1 is shorted directly to the compressor.

Any ideas?

 

[MikeP]

OK - got the FX 1 - which also controls the air handlers - working properly but the compressor still comes on anytime the breaker is on. I tested the Triac with a multimeter and it acts as if it is OK - no continuity between main terminals, then around 50 Ohms when the trigger terminal is touched to the appropriate main terminal. Is it possible for a triac to test ok with a multimeter but too fail to the "closed" position when line voltage is applied?

 

[MikeP]

Surprisingly (to me), it was the trigger. I had thought triggers only actuated the seawater pump. But I replaced the new (last year) trigger with an old trigger I had laying around and all worked perfectly.

I had forgotten that the problem with the comp staying on started when I replaced a faulty old style trigger with a new style last year when the bow system wouldn't turn on the SW pump. It appears that the new style triggers are sometimes problematic with the add-on digital controls. I discovered that on Cruisairs own site - they "upgraded" the triggers a few years ago and have had consistent issues with weird behavior on both their own digital controls and aftermarkets like the Coastal climate. THe old style triggers work fine with the controls but the new ones can work or not work or even be intermittent.

I'm not sure if they have a NEW new style trigger to correct the problem or not.

I haven't called them yet but I guess I'm going to...

At least I know WHAT the problem is...whether there is anything to be done about it except find old triggers, I don't know...

Here's the relevant quote from Dometic - note the second one. ALSO note - they don't offer a solution...

"There have been a few strange problems with the new style triggers
•Some triggers have failed partially and have caused the pump to run at half speed and caused the ac unit to shut down on HI-PS.
•If a new trigger is put in an old PWX box and the unit has had a SMX series retrofit, it will cause the compressor to run all the time."

 

[MikeP]

Just got off the phone with Dometic. They know that happens; they have no solution re aftermarket units. The trigger has different load characteristics than the old style and apparently, some of the digital units "see" something other than what is supposed to be there. They (Dometic) have made the necessary changes to their own digital (SMX) equipment to accommodate the new style triggers but they can't (of course) be responsible for Coastal Climate equipment.

So my next call is to coastal climate...

And I just got off the phone with them. The real tech guy wasn't available but the general response is the same as Dometic but in reverse...CC can't be responsible for changes made by Dometic! They said the tech guy would call me back but the initial thought is that the CC units were designed based on whatever cruise air had at the time; if cruise air has changed the trigger so that it reacts differently with the circuit, then the only solution is to use the "correct" triggers (which cruiser doesn't make any more.

Based on what I know up to this point, if anyone is considering installing CC digital controls for their cruise air systems, I suggest you rethink that and go with Cruisair SMX. My 4 CC boxes worked perfectly for years but that was on the old triggers, not the new ones.

FWIW, the triggers I am referring to is the one in the "Bow/galley" box and the one in the "Salon" box located in the eng room. THere are a mix of old/new triggers in the seawater pump box and they seem to work fine. I'm not sure I understand all the circuitry involved. Actually I am sure, I don't!

 

[MikeP]

Well, well, well...

I found a thread here from '08 that I participated in that basically answered the question - a resistor has to be added to the new style triggers - thanks Sky! Wish I had a better memory!

 

[TopHattandTails]

Yup. Added the resistor to the master and the bow. The 240vac units don't need them...(main salon and aft).

 

[SKYCHENEY]

Best fix is to just get rid of the PWX box altogether. If you have the CC control box, that is all that is needed. I kept one PWX. It controls the 36K BTU unit in the salon. The only reason I kept it is because Coastal could not tell me what the max size compressor was that they could start with their box.

 

[MikeP]

Sky and I talked on the phone last night and I am following his lead re replacing the PWXs in the eng room with my CCs instead of "tacking them [CCs]on" as they are now (per the CC instruction book). I recall that SPCoolin made the same suggestion last year on his site. It seemed like too much trouble at the time and unnecessary but, as Sky pointed out, it saves a lot of subsequent pain and annoyance. So I'll do the bow/galley unit today and see how that goes. Since it's not working anyway, it doesn't matter if there are unforeseen issues. I won't physically remove the oem PWX box(es) until the CCs are moved and tested to be operating properly.

 

[MikeP]

All done - CC unit is now in engine room/PWX is now an unconnected box. System is running fine in the "test" mode. After it runs OK for few hours I'll remove the PWX box and mount the CC box in its place. Nrxt up - same process for the Salon unit. I will have to get an "extension" cable for the control panel to mount it where it was located since now the panel is about 20 feet from the box instead of 2 feet. It seems to be working out well - again, thanks Sky!

 

[SKYCHENEY]

Mike,
Glad to hear you got it working. Maybe someday I'll get that way and check it out for myself.