Question on RVP heat pump

[Mavarick]

So I have the mod 6535 basement heat pump and was having a few cooling problems last time out. Not really bad, just seemed to be loosing some of it's effect in higher temp locations so I thought I would consider checking or charging the system with freon.
Does anyone know where the ports are located on the RVP unit before I tear into it? It only has one access panel that I remember and that is for electrical. I figure there should be a panel to get into the area for recharging it without dropping the unit right?

 

[Wizard46]

No panel, the unit has to be pulled out and the top removed. On mine there was no ports. A service tech can add ports if needed.

Duner has a good removal procedure here or over on IRV2

 

[Mavarick]

Darn, that's what I was afraid of. Did your tech add the ports by the compressors or did he add lines with the ports to make it so they were easier to get to?
I'm not sure mine even needs anything but thought it would be easy enough to check the Freon charge. Never thought of them not having ports already installed.

 

[Neal]

Run it until you are sure both compressors or running and leveled out (maybe 5 or 10 minutes with t-stat set extra cold) then take a temperature differential reading between the return air vent & a close supply vent. If you are getting 15 to 20 degree differential, you likely don't need any freon.

Darn, that's what I was afraid of. Did your tech add the ports by the compressors or did he add lines with the ports to make it so they were easier to get to?
I'm not sure mine even needs anything but thought it would be easy enough to check the Freon charge. Never thought of them not having ports already installed.

 

[Gary RV_Wizard]

A commonly reported problem with basement air is the loss of cooling where the duct runs up under the rear cap to the ceiling distribution ducts. On a hot sunny day the air can warm up quite a bit on its journey from basement to the outlets.

 

[Mavarick]

It just seems the heat pump will not maintain that difference of 15-18 degrees any more but we were in TN so it was a real challenge for it to begin with. I am going to check everything again now that we are back in WA to compare it to what I know it should be.
I did look at the ducting in the back Gary and it looked ok, or at least the same as it has been. That is what got me to thinking about the Freon. It still cools, just not as good as it did last year or the year before.
I thought checking Freon would be the easiest but it seems that will be the last option after I go through all the other motions.
Thx for the ideas though, I'll follow up.

 

[Wizard46]

Never did have to add freon to mine, the problem was that the seal had degraded where the elbow and the vertical duct was connected in the rear. Found that while pulling the unit. Repairing the seal and insulation on the duct made a really big difference.

 

[Mavarick]

Ok, thx Jerry. I will get into it this week hopefully, playing catch up from our trip.

 

[Mavarick]

Well, as much as I was hoping to find something wrong the heat pump is actually working quite well. I cleaned the return air filter, checked the operational lights for both stages on the pc board, measured the amps (15a and 22a), and checked the temp differential between the intake and one of the ceiling ducts which started at 24 degrees and slowly dropped to 20 as the outside ambient temp warmed up. It cooled the MH from 78 down to 71 in about an hour with outside ambient rising from 74 to 78 in the same time. All the ducts are working as they should so nothing left to check.
I have to assume the problem simply stemmed because we were in Tn when the ambient was mid-nineties with humidity between 55% and 75% and we were stuck in the direct sun, no shade to be found. The AC maintained an 8-9 degree differential by nightfall but I thought that was sort of weak. I know others have inst a supplemental AC on the roof to help and it also would have made a difference if there was some shade. All said it was a worthwhile trade for the fun we had in Knoxville, etc.
Thx again for all the suggestions.

 

[Wizard46]

I have come to the conclusion that they sized the unit just exactly right. No more room for really hot days. Those amps are exactly like mine.

 

[Gary RV_Wizard]

Sounds like your a/c system is "working as designed". RVs have a high rate of heat gain, either in the sun or a high ambient temperature. Insulation is relatively poor (thin walls), windows are a fairly high percentage of wall space, and all the walls are exterior heat gain walls. No attic either!

Some hot weather suggestions: Use your awning to shade at least one wall. Put insulation "pillows" in any roof vents and shower skylights. Put reflective tint on windows and use a sunshade or reflector in the windshield plus close the drapes or privacy shade. Every little bit helps.