A/C Delay - Coleman Mach 15

[rip]

I think my WindJammer has a Coleman Mach 15 A/C (15K btu). It's listed as a a Suburban model 48254C966. I'm wondering if it has a "time delay built in."

The Progressive Industries EMS (Electrical Management System) mentions setting a jumper depending on an a/c delay...

Consult you Air conditioner manual to see if it has a time delay built in, if so use the 15-second delay if not use the 136-second delay.

I looked through my a/c manual with no clue. I think Forest River puts similar a/c's on our various model trailers. Any of you air guys/gals know if our RV air has this delay?

[rip]

I did a search for "delay" and found a nice discussion under Georetown threads on EMS. Here, one member also mentioned not knowing if their a/c had a delay or not, and used the optimist approach to assume it did.

I'm only a borderline optimist, not quite that positive. I searched the a/c mfg site, and it seems specs mention a lot of pr style info, but nothing about "built-in delay."

Is there some way to monitor the a/c voltage or something to figure this delay thing out since manuals and literature side-step the issue? I consider myself to be electrical-stupid. I like to think I know just enough to be dangerous.

Would be nice to set the EMS jumper correctly.

[BarryD0706]

Start out by finding the circuit breaker for your AC unit in your breaker panel. Once you've done that, turn your AC on at the thermostat. After a minute or so, turn it off at the breaker. Wait 60 seconds and then turn it back on at the breaker. If it has a time delay, it won't run for another minute or three. If it comes on immediately, no time delay.

(Don't make that time any less than 60 seconds or you might damage your AC compressor.)

'Course you could also call the manufacturer.

Edit: I edited this post to indicate that the test should be performed by turning it off and back on at the breaker. (Originally it said to do it at the thermostat, but doing that may give the wrong conclusion.)

[rip]

Thanks Barry -

I followed both your original suggestions.

After the power on briefly, then off, then pause-60, then back on step using old thermostat technique, my a/c hestitated about 90 more seconds then powered on. Good indication that it has a time delay on thermostat actions.

I also emailed Airxcel tech support and inquired about that model number. Awaiting response.

The manual test was enough for my borderline optimism... fairly confident now that model has a delay, and an EMS jumper should be set for 15 sec (wait, see subsequent messages where we learned a delay was necessary).

Appreciate your response and help, Barry, and understand the principle behind your only-sixty-second caution.

Edited: This message was later edited with bold text to reflect step changes made in third post. See subsequent messages for revised results.

[rip]

Originally Posted by rip

I also emailed Airxcel tech support and inquired about that model number. Awaiting response.

Many of us are getting EMS (electrical management systems) that feature a delay setting that is short (15 sec) or long (2+ min) depending on our air conditioner's self-protection features.

I asked tech support at Airxcel about my 2013 Mach 15 model 48254C966air conditioner (a popular 15,000 btu a/c in Forest River products). He recommends the 2+ minute delay setting.

Here is the email dialog for the benefit of members with similar units...


----- Original Message ----- From: "Eric Botts" Airxcel
To: "Ray Rippstein"
Sent: Tuesday, April 02, 2013 8:25 AM
Subject: Re: Fwd: Start delay for model 48254C966


> The thermostat itself has a three minute time delay on break, but if you
> lose 120 volts, it does not interrupt the thermostat. With the thermostat
> still calling, as soon as the 120 volts returns, the AC will kick on
> immediately.
>
> --------------------------------------------------
> From: "Ray Rippstein"
> Sent: Monday, April 01, 2013 4:31 PM
> To: "Eric Botts" Airxcel
> Subject: Re: Fwd: Start delay for model 48254C966
>
>> Thanks Eric. Some friends gave me some on-off steps to try while I was
>> waiting for your response. These steps were trying to test for a delay
>> while avoiding building up too much head pressure.
>>
>> Yesterday, when I turned my unit on for 60 seconds, then off for 60
>> seconds, then back on, it waited for about two minutes before restarting.
>> That gave an impression that it might have a delay.
>>
>> Disappointing to hear that our new Mach 15 model 48254C966 units really
>> don't have a delay protection feature but may act like it. I'll tell my
>> friends the official bad news and broadcast info to the web forums where
>> we are discussing the EMS settings.
>>
>> Appreciate your response, it would be nice if Airxcel put info about which
>> units have the delay in their literature. That would really help the many
>> people now installing Electrical Management Systems in their RV's. -ray
>>
>>
>> ----- Original Message -----
>> From: "Eric Botts" Airxcel
>> To: "Ray Rippstein"
>> Sent: Monday, April 01, 2013 9:09 AM
>> Subject: Re: Fwd: Start delay for model 48254C966
>>
>>
>>> You will want to set the delay for at least two minutes. The air
>>> conditioner itself does not have a time delay, so if your were to drop
>>> 120 volts, and it returns within a short time, it would start the
>>> compressor under high head pressure, which can cause damage to the
>>> components of the AC or even the breaker for the AC.
>>>

[BarryD0706]

I know this is an old thread at this point but it needed an update. Ray, I certainly apologize for the faulty instructions I gave you to make that test. I didn't consider that the thermostat would not also lose power and that was a critical point. Thanks to you and your manufacturer for pointing that out.

I have edited my post #3 above to indicate that the test must be done by turning the AC off and back on at the circuit breaker instead of at the thermostat.

I verified that this works on my own RV and find that my Dometic AC and Dometic "Comfort Control Center 2" thermostat does not need a delay. (The thermostat is told when the AC loses power and goes into a day mode as indicated by an hour-glass symbol on the display.)

If you have a chance, it would be great if you could make the test the new way since we know you don't have a built-in delay and that would validate the test for the other situation. (Of course, no problem if you'd rather not do that.)

[rip]

Originally Posted by BarryD0706

...If you have a chance, it would be great if you could make the test the new way since we know you don't have a built-in delay and that would validate the test for the other situation. (Of course, no problem if you'd rather not do that.)

Thanks for your followup Barry.

I did your test the new way... located my AC circuit breaker, turn on AC at thermostat, after a minute or so turn off using the AC circuit breaker, waited 60 seconds then turn on the AC circuit breaker...

My AC fan and compressor started immediately.

This was different than when I turned the AC on and off and on using the thermostat. Using that technique, there was a delay.

This validates what the tech said about the thermostat having a delay when manually turned off, but not having a delay should the trailer lose power. Mine needs the EMS jumper set for a delay.

Thanks again for your follow through Barry, your "revised steps" yield proper results, showing my system functions different than yours. For other readers' benefit, my 2013 Coleman Mach 15 thermostat is also not digital and my AC unit is not like Barry's, I attached a pic of my thermostat.

[Witch Doctor]

It makes no difference if the stat or the ac has the time delay, I have the same stat and know if I turn the stat down then up there is a time delay built in, The circuit board in the compressor is what controls it. Turn your stat to bring on the unit, then raise the temp to shut it off, then turn it back on you will see it will not start for the delay in the compressor. Same as if you lost power......The 24 volts that operate the stat comes from the a/c not from anything else when set to a/c and then also gets in from your FAU when you run the heat.

[BarryD0706]

Originally Posted by gljurczyk

It makes no difference if the stat or the ac has the time delay, I have the same stat and know if I turn the stat down then up there is a time delay built in, The circuit board in the compressor is what controls it. Turn your stat to bring on the unit, then raise the temp to shut it off, then turn it back on you will see it will not start for the delay in the compressor. Same as if you lost power......The 24 volts that operate the stat comes from the a/c not from anything else when set to a/c and then also gets in from your FAU when you run the heat.

Go back and read post # 5. You are wrong.
Also, my Dometic stat is powered even when there is no power to the AC, so clearly it's not getting power from there. Ray was told by the company that makes his that the thermostat also has power when his AC is powered off. If the delay was in the compressor, then why did it come back on immediately when he restored power at the breaker?

[rip]

Originally Posted by gljurczyk

It makes no difference if the stat or the ac has the time delay, I have the same stat and know...

Some of what you said sounded ok, gljurczyk, while some was fairly confusing, perhaps misleading, and that can be dangerous, especially for members like me that don't have well grounded electric background.

I think I'll trust what the manufacturer's tech, Eric, said...

"The thermostat itself has a three minute time delay on break, but if you lose 120 volts, it does not interrupt the thermostat. With the thermostat still calling, as soon as the 120 volts returns, the AC will kick on immediately."

That (AC kicking on immediately) was confirmed in the revised testing steps that Barry suggested, which better simulate a short power interuption to the trailer while the AC is running.

Barry and I learned that although my thermostat has a 3 minute delay (as mentioned by the manufacturer tech) that protects the compressor during normal thermostat operation, that delay is not activated when there is a short power interuption to the trailer. And, that's when my compressor could get damaged. AC's like my model need to have their EMS set to delay restoration of interupted power, while AC's like Barry's would not.

Again, a salute to Barry for helping me pin down whether or not to set my EMS delay, and honorable mention to Eric, who pointed us in the right direction to get the test steps right.

[Witch Doctor]

If your unit did not come with a time delay relay to protect from power outages then I would suggest that you install a Robert Shaw time delay relay model # 3350-120, you can buy it on ebay for $12.95. This will stop you compressor from short cycling. Also I was not tiring to mislead anyone. Mine is protected already. The stat runs off the battery 12 volt, that's why you do not lose power in the stat when you lose the 115 volt. You might also want to invest in a surge protector that has a built in time delay after the power is lost. On sale now at CW $269.00. This will also protect your compressor from short cycling.

[BarryD0706]

Originally Posted by gljurczyk

If your unit did not come with a time delay relay to protect from power outages then I would suggest that you install a Robert Shaw time delay relay model # 3350-120, you can buy it on ebay for $12.95. This will stop you compressor from short cycling. Also I was not tiring to mislead anyone. Mine is protected already. The stat runs off the battery 12 volt, that's why you do not lose power in the stat when you lose the 115 volt. You might also want to invest in a surge protector that has a built in time delay after the power is lost. On sale now at CW $269.00. This will also protect your compressor from short cycling.

Yesterday you said that the stat runs off of 24v supplied from the compressor 120v supply. I'm glad you got that figured out.

And Dude, the whole point of this thread was to figure out if his surge protector needed to use a time delay!

[Witch Doctor]

Originally Posted by BarryD0706

Yesterday you said that the stat runs off of 24v supplied from the compressor 120v supply. I'm glad you got that figured out.

And Dude, the whole point of this thread was to figure out if his surge protector needed to use a time delay!

First of all my name is not dude, maybe you should show some respect, people are just tiring to help. Also their are tons of threads telling how important SURGE PROTECTORS ARE. Besides protecting your compressor as you stated it will also protect all the rest of your 115 volt running equipment, such as your Refer and TV. I hope you have that clear now DUDE...

[rip]

Originally Posted by gljurczyk

Ray, the stat is hooked to a board that is located in the return air, remove your filter and look up that's where it gets it power from the a/c........the same board also supply's you FAU power. The stat has no means of supplying 24 volt. It comes from the board where I just told you.

If your unit did not come with a time delay relay to protect from power outages then I would suggest that you install a Robert Shaw time delay relay model # 3350-120, you can buy it on ebay for $12.95. This will stop you compressor from short cycling. Also I was not tiring to mislead anyone. Mine is protected already. The stat runs off the battery 12 volt, that's why you do not lose power in the stat when you lose the 115 volt. You might also want to invest in a surge protector that has a built in time delay after the power is lost. On sale now at CW $269.00. This will also protect your compressor from short cycling.

gljurczyk, I believe you are trying to help. One of the things that confused or mislead me was when you mentioned "The 24 volts that operate the stat comes from the a/c not from anything else when set to a/c and then also gets in from your FAU when you run the heat." Then again, you said "the stat is hooked to a board that is located in the return air, remove your filter and look up that's where it gets it power from the a/c........the same board also supply's you FAU power. The stat has no means of supplying 24 volt. It comes from the board where I just told you."

My AC installation instructions say the thermostat 12 VDC positive/negative is supplied directly from the trailer's converter, not the AC as you said, with two supply leads, one +12 VDC red in color, one -12 VDC blue in color.

When instructions were discussing the thermostat wires (blue, yellow, green, & gray) you pointed out behind the filter, blue is for negative, and the others are for thermostat voltage to the relays, yellow compressor, green high fan, and gray low fan, all +12 VDC.

The "Robert Shaw time delay relay model # 3350-120" you mentioned is interesting but I'm unsure where I would hook that up so that it did not interfere with my thermostat's normal operating 3 minute delay and activate upon power loss to my trailer.

When you suggested "You might also want to invest in a surge protector that has a built in time delay after the power is lost," I had to smile because the testing we did was to determine which time delay setting to use on my Progressive Industries EMS (electrical management system) a popular surge-protector-plus-more system, the 15 second delay or the 2+ minute delay. The way my AC operates based on the testing, I would need the 2+ minute delay, while the way Barry's operates based on the testing, he could use the 15 second delay.

These are not meant to be disrespectful comments, but a lot of what you said confused me in the context of this thread. I think what you later said "The stat runs off the battery 12 volt, that's why you do not lose power in the stat when you lose the 115 volt," is now correct but different than what you said before.

I did learn something though but not exactly as you said it, gljurczyk, my thermostat supplies power to activate the AC relays through several color coded wires behind the filter. I think I'm stating what I learned correctly. Readers forgive me if I'm wrong. I attached a pic so others can see behind my filter...

[rip]

WOW, it's good that gljurczyk enticed me to remove my air filter and look at my AC wires to see what in the world he was talking about.

That big yellow wire in my previous message picture is 120 volt power. It's stiff and was bent down in a way that pressed hard on a sharp metal lip near the air reciever plenum. Yep, it was starting to cut thru.

Although it would probably trip the 20 amp circuit breaker if shorted, you never know. My confusion and curiousity had a reward for a change.

[rip]

Originally Posted by BarryD0706

Yesterday you said that the stat runs off of 24v supplied from the compressor 120v supply. I'm glad you got that figured out. And Dude, the whole point of this thread was to figure out if his surge protector needed to use a time delay!

Update... My Progressive Industries EMS worked well during a power interuption during a storm this week while I was working inside my trailer with the ac unit on... the EMS did not resume 115v service for 2min15sec, allowing my ac to equalize, and the ac did come back on immediately when 115v was restored by the EMS (just as it did in Barry's test steps).

And, Barry, don't be too hard on gljurczyk. I did more checking with Airxcel, and gljurczyk was describing how "park model" air conditioners work. Apparently, those models' thermostat operate at 24V and draw their voltage from the ac unit since "park models" don't have 12V batteries.

I learned that his ac setup is completely different than our "travel trailers" or "fifth wheels" and, I believe he was trying to point out that his park model unit does not behave nor need the same delay protection as yours or mine although it may still need surge protection.

I believe I'm becoming more ac-smart than ac-stupid thanks to everyone's patience here in teaching me (including the nice folks at Airxcel).