Dometic Penquin II Heat Pump Issues

[bcbowers]

We just experienced problems on both front & rear Penquin II heat pumps operating as air conditioners. The rear unit would short cycle for about 30 - seconds over & over again resulting in no cooling. The front unit was exhibiting some pronounced "chirping" & "rattling" noises and yet it was cooling adequately. I thought I would post what we did to correct both units in case you have a similar problem and desire to fix it yourself.

Here's what we discovered:

Front Unit:

We pulled the cover and observed that the "exhaust blower" assembly towards the back of the unit (comprised of sheet metal) had foil tape around the edges which had deteriorated and split. The sheet metal was effectively "rattling" when running. There are also overlapping tabs on each side that we believe were causing the "chirping" noise. We simply cleaned off the old foil tape and re-taped the edges appropriately. The unit runs quietly once again (or atleast as quiet as an old Penquin II heat pump can run!). I now carry some foil tape for future use.

Second Unit:

We tried various settings on the Comfort Control Center and discovered that the "Fan Only" did NOT work when selecting "Low" speed. We returned the CCC setting to "Cool" and pulled the cover to observe its operation (DO NOT STICK FINGERS OR ANYTHING ELSE INTO THE UNIT WITHOUT A COVER!!!). We observed that the compressor would run but NO fan. We surmised that the "Auto" fan setting actually starts in "Low" and then increases to "High" as necessary. So, we set the CCC to "Fan High" resulting normal operation which verifies that the problem is NO "Fan Low" operation.

NOTE: This is where more serious testing with a voltmeter is required. If you're not comfortable with performing some electrical testing I suggest that you obtain a qualified technician to assist.

The schematic diagram included with the operation & installation manuals indicates that the motor is actually a 3 - speed motor (LO, MED, HI) but "MED" is NOT connected (Yellow Wire). We removed the side cover for the control board and located the terminals associated with the fan speed control. The "LO" speed is a RED wire with a female spade type connector connected to terminal "T3". We used clip leads to measure voltage on "T3" and retested "Fan Low". Behold, now it was working to our surprise. We turned the unit off, disconnected the voltmeter and retested it on "Fan Low". It failed to once again. We pulled the red wire (spade connector) and discovered that it was crimped on the insulation ONLY! There was NO actual wire protruding from the red insulation as you might expect. So, we removed the connector, re-crimped a new one, and replaced it back on "T3". VOILA!!! The rear unit now functions normally.

If you need any pictures I can post some. Please PM me with any questions.

[MtnTrek]

Great write up! Thanks for spreading the wealth (of information). You're a journeyman tech & proficient tech writer.

I'm thinking the fan speeds in Auto cool are determined by the CCC logic, deviation from the temp set-point. Controlled space temp 3-5-8 deg. above set-point bumps it up to higher FS etc. Inverse of this as it's cooling down.
Hard to imagine that bad crimp rearing it's ugly head this far along, huh? Are they original units?

Be well.
Be well.

[Old Scout]

Duct tape--two rolls, regular and foil--don't leave home without them...

[bcbowers]

Pictures of the front Penquin Heat Pump that was "rattling" and "chirping":

Here is what we found after removing the shroud:



We removed the old tape and now you can see the overlapping tabs were probably causing the "chirping" noise:



New foil tape applied:



Now I've ordered new shrouds since the old ones are badly broken and cracked. The front unit is missing foam sealing strips where as the rear unit has them glued to the shroud. Supposedly, the new shrouds (obtained from PPL) have the appropriate foam. They should be much more efficient once completed.

[tiredvet]

Great write-up Bob.Always love the photos.

[Jeeper64060]

FYI - I just replaced a front shroud and the foam was glued to the air conditioner body - there were no foam strips on the cover. I used some trim adhesive to re-attach in a couple of spots. My front one is weak and cycling frequently. I cleaned it and installed the new cover and it did "OK" on our trip to Arkansas. It was not real hot so I have my doubts if we go anywhere hotter.

[Smitty77]

Thanks for sharing, and good investigation to discover the non stopped wire!

Smitty

[bcbowers]

I've had a lot of problems in the past with the front shroud coming loose while traveling and assumed that the problem lies with the shrouds being bigger than the Penquin frame. I had previously used weatherstripping around the edge thinking that it needed to be sealed. Wrong!

The secret to the shroud is having good foam attached to the top of the unit or inside the shroud AND mounting it securely. The foam seals the appropriate chamber of the heat pump per the provided diagram.

I received the new Dometic Penquin shrouds. The new shrouds come with the required strips of sticky-backed foam and instructions on how to apply it. Once properly applied (on top of the unit is preferred), the shroud has to be pushed down for proper mounting which makes perfect sense for a good seal.

Now for the actual shroud mounting. They ARE still too large for a perfect fit so some space exists between the shroud and the Penquin frame. The screws tend to pull the plastic shroud in at the screw locations thus applying constant stress which causes cracking and possible breaking (mine were in HORRIBLE shape). We used 1/8" nylon spacers (ACE Hardware) at each screw location between the frame and the shroud which makes for a good tight fit without distorting the shroud. Previously, we had also opted for #10 self tapping screws (normally #8) with washers and lock washers so we reused them. Whatever it takes to keep the front shroud from coming loose!!!

Interestingly, my old front shroud had NO vent holes or slots on the rear DS. This is NOT proper. The squirrel cage needs to push air through the rear condenser and out the rear DS vent as well as down. If there's no venting then the condenser cooling is being restricted. Make sure your shroud is vented!

Just wanted to provide my final fixes to my Penquin heat pumps. They're a little quieter and seem to be more efficient. Atleast I know they're operating at their best.

[Jeeper64060]

Bob my new shroud did not have vent holes - so I made some with a 1" forstner bit. The shroud is an aftermarket brand. Just did not look right to me.

[bcbowers]

Good move Tim!

My front shroud had been replaced (twice) by a dealer in Colorado who must have purchased an aftermarket brand. I ASSUMED they put the right cover on it. And, there was some foam missing from the top of the unit.

If you simply look at the rear blower chamber that cools the condenser you realize that it needs to move a BUNCH of air to be efficient. Without the side vent ALL of the air must divert downward around the outside edge. Even with the vent there is a tremendous amount of air coming out around the outside edge as well as the vent. This is also why having good foam rubber to seal the chamber is important.

It'll be 117 degrees here in Surprise, AZ by Monday so both AC units will be struggling to keep up; especially when my son & his wife set the thermostat for 77!? Good thing we have solar!!!

[Jeeper64060]

The one I got was an ICON brand. It fits good and is a little thicker than the original. No vent holes though and no foam so be ready to deal with that.


https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[JC2]

Originally Posted by Jeeper64060

The one I got was an ICON brand. It fits good and is a little thicker than the original. No vent holes though and no foam so be ready to deal with that.


https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Also ordered (2) of the above last year and realized they were the incorrect ones since they had no exhaust vents. Returned them and got the following with vents and they work great. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[bcbowers]

Guys, I purchased mine from American RV Company for $93.25. They are Dometic replacement shrouds (proper vent holes) with foam rubber.

Dometic 3308047.004 Shroud Shell White 15,000 BTU Trailer Camper RV