New Coleman Mach A/C condensation leaking into coach after shutdown

[FormerBoater]

There are numerous discussions on this excellent forum regarding condensation leaking into units either while running or after shutdown.


Most good advice regarding units that leak only after shutdown point to dirty filter or icing of the coils due to low refrigerant levels or some other malfunction in the internal cooling system which leads to icing.


Theory is that once the unit shuts down, ambient temperatures melt the ice and then the condensation starts a heavy drip as the ice melts quickly (mid-90's temps here).



I do not know if the coils are actually icing up, I do know that there is no condensation drip at all when the unit is running. About 2-3 minutes after shutdown the drip presents itself.


Had a nice little downpour yesterday while the coach was in storage and there was no water intrusion at all, so I think the gasket(s) are fine.


As this is a brand new unit, are there any other things that I am not considering?



Have called the service dept that installed it last week and hope to get in this week.


Should I request a replacement unit?

[FormerBoater]

Really hoping to catch Old Biscuit's eye on this one.


Will be talking to the Service Dept that installed the unit tomorrow.


Anyone?

[luvlabs]

Does your unit normally get rid of condensation by allowing it to run across the roof or is there a sump pump/tubing that deposits the condensation in a specific location? If it normally runs across the roof, remove the shroud and clean out the drain holes along the base. If it pumps it out, it could be a failed pump or the tubing could just be plugged. Either way, it's back on the roof.

BTW, the evaporator coil can easily ice up if you are in an area of high humidity and set the temperature below 75 and turn the fan on low.

[FormerBoater]

Originally Posted by luvlabs

Does your unit normally get rid of condensation by allowing it to run across the roof or is there a sump pump/tubing that deposits the condensation in a specific location? If it normally runs across the roof, remove the shroud and clean out the drain holes along the base. If it pumps it out, it could be a failed pump or the tubing could just be plugged. Either way, it's back on the roof.

BTW, the evaporator coil can easily ice up if you are in an area of high humidity and set the temperature below 75 and turn the fan on low.

The condensation should just run off the roof.


This is a BRAND NEW unit, so the drain holes should be free and clear of any debris.


Ran the unit for one hour yesterday and took the coach out for a little exercise. Fan was on high, humidity was high and unit did not cycle until I adjusted the thermostat when I returned to the storage yard.


No condensation drip at all until I shut down the unit. Then 2-3 minutes later a substantial amount of condensation dripped onto the floor and wet part of the headliner.


The rear unit was also running under the same conditions. It is 21 years old and no condensation drip at all (and it never has dripped). It was set on a low fan setting which has always been my practice for the rear unit.


I am thinking that this new unit may have some "factory" issues. Perhaps it was shipped low on refrigerant.


Have appt. with the dealer next Tuesday.


Any input appreciated!!

[gramps66]

Had a new Coleman put in a couple years ago in my holiday rambler they forgot to hook up the hose for the drain
I drilled holes in the tray next to the sump so when it overflowed it went on the roof and not inside the coach

[Old-Biscuit]

While unit is running condensation could be pulled over by fan and discharged into plenum/air ducts.....then when you shut down condensate over whelms evap coil drip pan drains and overflows into the ceiling grille dripping out into the RV


Remove the return air filter.that should give you visual/hands on access to evap coil and drip pan


High humidity will cause high condensation
You can stick you fingers into drip pan/use a mirror etc to check level of water in drip pan


**does water --any water--run off the roof when running this A/ Unit?
Should have some and if humid should be lots


New unit doesn't mean drip pan drains are clear of debris OR blocked cause A/C Unit was over-tightened (should be gap between roof and bottom of A/C Unit pan so drain holes can flow out onto roof

[FormerBoater]

Thank you for your input Old Biscuit!


It may well be that the mounting bolts are over-tightened as there is almost no condensation run-off on the roof.



Will hopefully find out what the problem is next Tuesday.


Happy 4th of July to all!!!

[Old-Biscuit]

Roof A/C gasket is 1" thick.....when installed it should be compressed no more then 1/2


Hold down bolts should be 'finger tight' then just SNUG
(20 INCH Pounds should one get technical)

[FormerBoater]

Originally Posted by Old-Biscuit

Roof A/C gasket is 1" thick.....when installed it should be compressed no more then 1/2


Hold down bolts should be 'finger tight' then just SNUG
(20 INCH Pounds should one get technical)

I can now see that on the driver's side the gasket is significantly over tightened.


The indicator that should be flush on the gasket is actually bowed!


Should I insist that they replace the gasket as the installation looks like it was subject to some "rookie moves"?

[Old-Biscuit]

Originally Posted by FormerBoater

I can now see that on the driver's side the gasket is significantly over tightened.


The indicator that should be flush on the gasket is actually bowed!


Should I insist that they replace the gasket as the installation looks like it was subject to some "rookie moves"?

YES..........
Brand NEW Unit.......gasket has been crushed/distorted

Have them make it right.....AND show you the Gasket that was replaced!

[FormerBoater]

Gasket was replaced and tightened to spec, but the problem persisted!


Service Center took off all of the covers to find that the drain pan had a crack in it and a good size screw protruding thru it.


Unit was replaced with another new Coleman Mach 3+ and the problem is solved!

[leadman]

This is the age of almost every mechanic using some type of cordless device to tighten screws and bolts, etc. Most have no idea how tight they are turning the fastener.
My wife bought me a Milwaukee 1/4" drill cordless impact last Xmas, I decided to see how tight it would turn a lug nut on my truck. It hit #160 ! Hard to believe so I confirmed it with a second test. Same thing. Amazing.
The gasket is clearly marked as to when to stop.

Glad the shop found the problem.