A/C not getting cold - intermittant - ideas?

John_Canfield · 03-03-2006, 12:49 PM

From sunny Vinton,LA:

We're two for two - yesterday and again today when trying to turn on A/C after getting squared away at the campground, it only blew ambient temperature air. This happened once before a few months ago. The situation:

-Heat pump works so I know the freon is okay and there is integrity in the piping
-When in AC mode with warm air blowing I can hear the compressors running
-I have to turn the thermostat off and on several times and let the thing cycle on to get the AC blowing cold air
-Today I cycled it to heat pump mode, then back to AC and then we had cold air (after turning it off and on four other times)

I talked to Winnebago service about this problem yesterday and he thought it might be a bad thermostat. I thought it might be a sticking reversing valve but he said those are pretty reliable.

Anybody have any ideas?

John_Canfield · 03-03-2006, 12:49 PM

From sunny Vinton,LA:

We're two for two - yesterday and again today when trying to turn on A/C after getting squared away at the campground, it only blew ambient temperature air. This happened once before a few months ago. The situation:

-Heat pump works so I know the freon is okay and there is integrity in the piping
-When in AC mode with warm air blowing I can hear the compressors running
-I have to turn the thermostat off and on several times and let the thing cycle on to get the AC blowing cold air
-Today I cycled it to heat pump mode, then back to AC and then we had cold air (after turning it off and on four other times)

I talked to Winnebago service about this problem yesterday and he thought it might be a bad thermostat. I thought it might be a sticking reversing valve but he said those are pretty reliable.

Anybody have any ideas?

Bob G · 03-03-2006, 02:04 PM

Hay John,

Think about this.. The thermostat controls the compressor operation. The heat/cool switch controls the reversing valve.
Do you have a manual switch for heat cool?
Check for voltage at the reversing valve. I think that when it's de-energized it's in heat mode.
It could be the valve or the switch or the wiring in between.

DancinCampers · 03-03-2006, 02:27 PM

Hi John,

When you say unit running, compressors running, you get ambient air? I would think you would be getting either hot or cold, but not ambient.

If you are getting ambient air with both compressors running then it could be that one is in cooling mode & the other in heating mode, basically cancelling each other out.

I would first try shutting off the breaker to the #2 compressor & see how it operates & cycles on just the first one. According to my manual, in cooling mode the unit will use 1 or 2 compressors, depending on the cooling load requirements, but in heating mode it always uses both as long as power is available.

The reversing valves default to cooling mode, are energized in heating mode. So if tstat is set on cool and one is operating in heating mode it is either stuck, or the relay in the basement unit is stuck, or the tstat is providing the control voltage.

BTW, I believe these basement units have 2 yr warranties, not sure if that includes T-stat or not.

Hitchhiker · 03-03-2006, 02:28 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I have to turn the thermostat off and on several times and let the thing cycle on to get the AC blowing cold air </div></BLOCKQUOTE>

Maybe it's 'icing up' on the evaporator coils and blocking the air flow.

Low on freon and poor air movement over the evaporator coils are two causes for icing up.

John_Canfield · 03-03-2006, 02:38 PM

Hey Bobby! - Looks like the situation is a lot more complicated than first thought as Dan points out.

Dan - yesterday I was getting 91 degree air out of the duct (about 80 degrees ambient outside air) in the cool mode. Today I was getting about 80 degree air out of the duct in cool mode with about 76 degree ambient outside air.

I'm wondering if the problem isn't one of the reversing valves - I suppose there must be two since there are two compressors. Maybe one is in cool mode and one stuck in heat mode.

We'll be spending a few days in Austin starting tomorrow so I might try to do a little troubleshooting.

Fortunately everything is still in warranty

AdrianLee · 03-03-2006, 03:20 PM

John,

Isn't Vinton one of the real garden spots

? I do notremember an RV park north of I10. The only one I know about is near the casino there.

Austin is really great so enjoy. You are missing one of the really nice areas too. San Antonio is super. We stayed there 3 days on our way to CA.

rebelsbeach · 03-03-2006, 03:33 PM

Hey John, I hear they're predicting blizzard like conditions at Iron Horse RV in San Antonio....better wait on that Howard Precision Center Steer install...Phenom weather just in that neighborhood...

DancinCampers · 03-03-2006, 03:35 PM

John,

From what I have been able to determine, this is how the compressors are controlled.

When T-stat is set to cool, and temp is set 2 deg or less below room temp, control voltage is sent on wire Y-1 to start #1 compressor. If temp is set more than 2 deg below room temp then control voltage is sent on Y-1 to start #1 compressor, then after a built in 30 sec time delay control voltage is sent to Y-2 to start #2 compressor. After unit reaches set temp, on the next cycle the #1 compressor will come on and if it can maintain set temp within the 2 deg #2 won't come on. If the room temp rises above the 2 deg while compressor #1 is running then #2 will come on line. The T-stat controls this function, along with the fan speeds you have set, lo or hi.

When T-stat is set to electric heat mode, and temp is set above room temp, then control voltage is sent on wire W to the control board in the basement unit. The control board then turns on #1 compressor & #2 compressor (after a built in time delay) & also turns on HI speed indoor blower (regardless of fan speed you have selected on the T-stat), along with activating the reversing valves. The t-stat only controls the temp at which both compressors turn on & off. (Of course, in the heat mode it will also control the gas furnace, but that is a separate discussion)

To trouble shoot, I would try the following:

-You need to see amp draw, so either run generator or use 30 amp service. (On my unit I can trick the EMS into thinking I am on 30 amp by turning off circuit breaker to hot water heater before plugging into 50 amps)

-Turn off circuit breaker to #2 compressor

-Set T-stat to cool & temp below room temp

--Monitor amps as #1 compressor comes on line. Should be about 13 amp rise after it settles down. (If you are seeing significantly less amp draw, then possible #1 is running, but freon is low. The compressor is a vapor pump, low freon means it does not have to work very hard.

-Check air temp from ducts, if cool then #1 is ok.

-Turn T-stat off, turn circuit breaker to #1 off, # 2 on.

-Turn T-stat to cool, & set temp more than 2 deg below room temp.

-T-stat will click for stage one, only fan should come on. After 30 sec #2 compressor should come on.

-Again, check amp draw & duct temp.

-If T-stat is set to cool, & temp is set to more than 2 deg below room temp, & circuit breakers for #1 & #2 compressor are turned on, then you should be able to see the amps increase as #1 comes on line & again when #2 comes on line.

Hope this is not too confuseing, but I think in order to troubleshoot you need to see the amps & duct temp.

KennethM · 03-04-2006, 01:25 AM

John,
I had the same problem when first got our coach not quite as warm but AC did not cool well after heat pump mode was used. Once I read how this system is not really a true heat pump but just reversing valves my solution was to only use it on AC and furnace for heat. Many will will find this unacceptable but the AC in my coach now blows very cold air with 1 or 2 compressors online. There was a lengthly post couple of years ago by a engineer who had problems with his system and work with Coleman to fix it himself but really gave detailed explanation of the the workings or lack of for the True Air system.

John_Canfield · 03-04-2006, 02:05 AM

Dan - thanks so much for taking the time to provide detailed troubleshooting information! Even through there is a Winnie dealer south of Austin, I think it best for me to have a good idea about the problem before I let them get involved. I'll work on it next week.

Ah yes - Vinton. The entire I-10 trek from MS to here looked in many places like like a junk yard combined with a housing project. We saw campers in tents in a field by a truck stop (around Gulfport or Biloxi I think.) Still many blue tarps here and there.

At the Vinton RV park, their sign showing where to turn into it was missing and of course our laptop/GPS decided to go south a mile before - so we missed our turn. I went ballistic about the missing sign - how much work is it to buy a 4x8 sheet of plywood, a can of spray paint and two 4x4 posts? Jane had to calm me down.

Sorry - a little off OT

"007" · 03-04-2006, 02:23 AM

John, relax

your not running the shop

anymore, plus your a fulltimer.

"007"

ichn2go · 03-05-2006, 04:57 AM

Thank You,,Jane.

Don (W5IT) · 03-05-2006, 05:17 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I went ballistic about the missing sign - how much work is it to buy a 4x8 sheet of plywood, a can of spray paint and two 4x4 posts? Jane had to calm me down. </div></BLOCKQUOTE>

That is provided there is some plywood to be had.

Just remember John, just a few miles south of where you are parked enitre TOWNS were wiped off the map by Rita....

Folks lost eerything they had, owned built. Many lost their life.........

So looking at the "Big picture of the area" missing an exit due to a sign being missing is trivial.

Now on a more plesant note.....................

If I had KNOWN you were in the area (Baton Rouge) I would have invited ya in for a visit. Only 30 amp hookups at our shop, but the price is right....

IRV2.COM members are welcome to stop and spend a couple days visitin. (It won't cost ya anything either)

Might even have fixed your A\C.

But if ya stay more than seven days we will put you to work!

John_Canfield · 03-05-2006, 05:34 AM

Don - yes - those folks suffered quite a bit and I certainly feel for them. We had our moments also living in Central Florida (but not as bad as the Gulf coast fortunately.) Had a tree smash my storage buliding in 2004; and lost three others. No power, no phone, no cable, no gas - ah yes, I remember it well!

Darn - I'm sorry I passed you by! Thanks a bunch for the invite anyway. Today is a rest and play day here in Austin; tomorrow I'll get to work troubleshooting the AC.

Don (W5IT) · 03-05-2006, 05:47 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">tomorrow I'll get to work troubleshooting the AC. </div></BLOCKQUOTE>

Hit it

with a BIGGER hammer.

ronboc · 03-23-2006, 07:57 AM

Sorry to drag this a bit off-topic, but DancinCampers, what did you mean by being able to trick your EMS into thinking it's on a 30Amp supply by turning off your hot-water-heater first?

Ok, back on-topic...

Thanks!
Ron

arkaussie · 03-23-2006, 02:26 PM

John,
You may want to get under under the left hand back corner of your coach and look up to see with a flash light if the vertical duct run has split open. You may well feel the cold air. I found this was a problem on mine. After removing a side panel inside engine bay I was able to close it up with the metal tape. I hope to put some insulation around as much of the duct as I can most likely with rigid insulation to get further up than I can reach.

I also read and found it to be true that if you leave your fan running all the time it will maintain the temp better.

Keep us posted with the outcome of your problem.

TheRVGuy · 03-23-2006, 05:31 PM

John,

You seem pretty competent in troubleshooting from what you have posted. Therefore, I would suggest that you call Dick Wade at Coleman-RVP 316.832.4357. Dick is a great guy, provides all the dealer and distributor training, and will most probably be able to send you to the top 2-3 things that are affecting your system. It would be helpful for you to have the model and serial number from your A/C unit when you call him.

Let me know if this doesn't get you some results and we'll be glad to guide you in specific evaluations.

Mike & Lisa

John_Canfield · 03-24-2006, 03:52 AM

The duct work is okay - long ago I read a thread about the duct work seperating on some coaches (ouch!)

Mike - the tech at Crestview RV in Buda, TX who was troubleshooting my complaint showed me how to gain access to the circuit board and where the telltale green LED was; he said the next time it fails to go into cool mode look at the LED to see what sequence it is flashing and then call RVP for some help.

Naturally the AC has been cooling every time since our service visit - maybe we scared it into operating