Dash A/C question

Daysu47 · 07-29-2008, 10:33 AM

When using the dash A/C while traveling it works great but when I exit the freeway and am at a slow speed the A/C begins to blow warm air. This shouldn't be one would think.

Just for the record, I had the complete A/C unit repaired, vacuum unit, and entire A/C unit was removed and replaced during repairs.

Any ideas, suggestions, etc.?

David

Daysu47 · 07-29-2008, 10:33 AM

When using the dash A/C while traveling it works great but when I exit the freeway and am at a slow speed the A/C begins to blow warm air. This shouldn't be one would think.

Just for the record, I had the complete A/C unit repaired, vacuum unit, and entire A/C unit was removed and replaced during repairs.

Any ideas, suggestions, etc.?

David

JC2 · 07-29-2008, 01:55 PM

Anytime we need the AC, we turn the generator on and use the roof air(s). More efficent, then the dash air, uses less fuel and excercises the gennie. I believe most dash airs are notoriously inefficent and underpowered for MH's. We just returned from a 1200 mile round trip from the IRV2 annual rally and used one or more of the roof airs as needed and still averaged 8.5 MPG running 62-65 MPH.

Pubtym · 07-29-2008, 02:05 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Daysu47:
When using the dash A/C while traveling it works great but when I exit the freeway and am at a slow speed the A/C begins to blow warm air. This shouldn't be one would think.

Just for the record, I had the complete A/C unit repaired, vacuum unit, and entire A/C unit was removed and replaced during repairs.

Any ideas, suggestions, etc.?

David </div></BLOCKQUOTE>

First suggestion would be to run Dash Air on MAX/AC. This recirculates/continues to cool/dehumidify only the interior driver and pax compartment air. If you are running "Normal A/C"...and you slow to a stop...your A/C now begins to import superheated engine compartment air into the A/C outside air intake. Superheated air + cold A/C air = warm air into driver and pax compartment vents.

Second suggestion: Check the return air vent for the Max Air. It is usually under dash on floor on Pax side. Sometimes hamburger wrappers etc...purses..block/restrict that returning cool air.

Third Suggestion: Use your defrost fans on low speed when using Dash Air..point them toward the outer edge of front windshield..This greatly adds to inside cool air movement and evaporation.

Paul T · 07-29-2008, 02:53 PM

Mine acts just like yours does Daysu47. And, for the record, my Ford Explorer's a/c is much less effective at idle or very low speeds. If your workhorse didn't have a house behind the cab I think you would find the a/c as effective as any other truck cab.

JC2 – And what is the fuel burn of your generator per hour???? Sounds like you must have had a nice down hill trip with a good tail wind IMHO. I just don't think I get the kind of free lunch you described. Every time I've tried running my generator enroute as you describe my mpg goes down significantly.

Pubtym · 07-29-2008, 03:15 PM

More info..

http://irv2.infopop.cc/eve/forums/a/tpc/f/8626012545/m/...041019034#6041019034

Trek-Cyclist · 07-30-2008, 04:38 AM

I increase my fuel mileage by using the Generator with the basement air... The exhaust from the Generator pushes the Motorhome forward ever so slightly you can hardly feel it, but it's there

jk_and_dog · 07-30-2008, 04:47 AM

I also use the house air to cool down when the inside temps get to be uncomfortable. My Gennie only uses a couple of gallons, maybe 3 to 4 over a 12 to 15 hour period, very efficient. I measured it when I got the MH. Still fuel consumption on the readout system does not take into account the gennie fuel so my mpg is strickly from engine use and not the combo gennie and engine. I'm getting around 8.2 with the S-10 in tow. 36' 07 journey /31K on the east coast.

glenda1908 · 07-30-2008, 04:55 AM

We had the same problem when we had our Chieftain. If I remember, we were told it was a design problem with the location of the compressor in the Workhorse chassy. The warm air from the engine would overide the cool air. We used the house air when we needed it and just learned to live with it. I know this doesn't solve the problem, but might explain it.

Petro · 07-30-2008, 04:56 AM

David;

My Chieftain acts just like yours. Pubtym says it clearly the way it is. When we get in to a city or campground where there is a wait we just fire up the central a/c.

Don

Rocket Heart · 07-30-2008, 05:43 AM

I think it's inherent with the beast. Even cars will warm when going very slow or stopped. Like some of the others here I use my house air to keep cool. Works great and costs less.

JC2 · 07-31-2008, 12:39 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Paul T:
Mine acts just like yours does Daysu47. And, for the record, my Ford Explorer's a/c is much less effective at idle or very low speeds. If your workhorse didn't have a house behind the cab I think you would find the a/c as effective as any other truck cab.

JC2 – And what is the fuel burn of your generator per hour???? Sounds like you must have had a nice down hill trip with a good tail wind IMHO. I just don't think I get the kind of free lunch you described. Every time I've tried running my generator enroute as you describe my mpg goes down significantly. </div></BLOCKQUOTE>

I guess you could say I was going downhill since we went down to Tx. Fortunately most of the terrain was relatively flat with little wind. Coming back a different way, the terrain was again pretty flat with a little tail wind. Most of the time we will get consistent 8-8.5 MPG unless we get into hills/wind then the MPG will drop to 7.5 +-. If I start pushing it consistently over 65, then the MPG will drop to between 7.5-8.0 MPG. Over all I've been pleased with the mileage using the gennie and roof air(s) and estimate the fuel usage to be between .5/.6 gal per hour. I'm sure some of this can be attributed to the following:
1. Engine oil/filter and gas/air filter changed at 1yr/5000 miles using conventional dino oil.
2. Ultra Power upgrade seemed to help with increased power and 3/4-1 MPG increase.
3. Using a light foot on the gas/brake pedals.
4. Taylor 409 plug wires.
5. AC 41-932 plugs gapped at .045.
6. Tire pressure @ 90# all around.
One thing I've always believed in is good/consistent maintence and it will pay off. I'm sure I do some things before they are due but the cost IMHO is worth it.
I could go on and on but I might jinx myself.

JC2 · 07-31-2008, 12:46 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Trek-Cyclist:
I increase my fuel mileage by using the Generator with the basement air... The exhaust from the Generator pushes the Motorhome forward ever so slightly you can hardly feel it, but it's there

</div></BLOCKQUOTE>

Trek-Cyclist · 07-31-2008, 01:55 PM

OK now compute your mileage using a pencil paper or calculator... Not the dash computer readout... Your mileage may very...I bet...

Paul T · 07-31-2008, 02:41 PM

To substantiate an earlier suggestion that everything would work much better with adequate floor insulation I suggest you duplicate my experience an hour ago. I got in my heat soaked RV with OAT above 90 degrees. When first started and driving slow the dash a/c worked great with very cool air being pushed out. 45 minutes later,after the engine had had a chance too heat everything up,it was back to acting as if it needed a Freon charge at low speeds and idle.

Reference gas mileage, Trek-Cyclist said it well. Anyone who thinks the mpg readout on the dash has anything to do with your actual mpg should really defer to pen and paper before telling us what kind of gas mileage they are getting. I've been really fooled by monitoring the avg mpg readout to the extent that I strongly suggest it be ignored.

j griff · 07-31-2008, 02:56 PM

I'm sure most of you know that the dash "Avg MPG" readout is for the last 50 miles only. I have alwys computed my gas mileage = on all vehicles = the old fashioned way. I always fill my tank to the same level (as nearly as possible) and compute the mileage manually (now have developed a computer spread sheet to track MH mileage and expense)
Bottom line - I can pull in to my drive after a 1000 mile trip with the dash reading 9.0 MPG - but a manual calcultion indicates 7.5. In fact for the life of this coach the overall average MPG is 7.549.
Cheers and Happy Trails !!

Trek-Cyclist · 08-01-2008, 01:10 AM

I had Dash A/C problems when the coach was a year old. After 2 trips to the Service facility it works great and it's been 5 years.
They recharged the system the first time and used dye, found a leak in the condenser. Replaced and recharged. After 6 months the Thermostat went bad had that replaced. Now it gets very cold very fast and stays that way. I only use the dash A/C in Max A/C mode never A/C. There are times when I have to turn it down, it gets too cold, really. Not bragging just works good...

Note: To check and see if A/C fans are working:
When getting ready to leave a place I start the MH up select MAX A/C and let it warm up while unhooking or hooking up the Toad. You'll hear the A/C cooling fans come on. When that happens I know the Motor is warmed up the A/C is working and we're ready to roll.
I would get the system Check out by a professional.. Like I said it's been great for awhile now, knock on wood... Also, 99% of my driving is Interstate/Highway.
My 2 cents...

Daysu47 · 08-01-2008, 07:01 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JC2:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Paul T:
Mine acts just like yours does Daysu47. And, for the record, my Ford Explorer's a/c is much less effective at idle or very low speeds. If your workhorse didn't have a house behind the cab I think you would find the a/c as effective as any other truck cab.

JC2 – And what is the fuel burn of your generator per hour???? Sounds like you must have had a nice down hill trip with a good tail wind IMHO. I just don't think I get the kind of free lunch you described. Every time I've tried running my generator enroute as you describe my mpg goes down significantly. </div></BLOCKQUOTE>

I guess you could say I was going downhill since we went down to Tx. Fortunately most of the terrain was relatively flat with little wind. Coming back a different way, the terrain was again pretty flat with a little tail wind. Most of the time we will get consistent 8-8.5 MPG unless we get into hills/wind then the MPG will drop to 7.5 +-. If I start pushing it consistently over 65, then the MPG will drop to between 7.5-8.0 MPG. Over all I've been pleased with the mileage using the gennie and roof air(s) and estimate the fuel usage to be between .5/.6 gal per hour. I'm sure some of this can be attributed to the following:
1. Engine oil/filter and gas/air filter changed at 1yr/5000 miles using conventional dino oil.
2. Ultra Power upgrade seemed to help with increased power and 3/4-1 MPG increase.
3. Using a light foot on the gas/brake pedals.
4. Taylor 409 plug wires.
5. AC 41-932 plugs gapped at .045.
6. Tire pressure @ 90# all around.
One thing I've always believed in is good/consistent maintence and it will pay off. I'm sure I do some things before they are due but the cost IMHO is worth it.
I could go on and on but I might jinx myself.

</div></BLOCKQUOTE>

JC2, I concur with about everything you stated except as noted.

For #1 I use Moble 1 Syn.
#2 Have same and agree with results
#3 Agree
#4 Have same
#5 Have same
#6 Do the same - Sentry Tire Monitoring sys.
#7 Dash air on most of the time, about 60%, when hot outside.

We just came back from a vacation from San Diego to Iowa and back; 3890 miles, averaged 8.1 mpg for the entire trip. This was achieved by simple math, total miles driven and total gallons used on trip. Noted though, after some fill ups averaged 6.5-7.5 mpg and after other fill ups averaged 8.5-9.5 mpg. 99% freeway driving, 66mph, constantly on cruise control, and no toad. I have a Scan Gauge II and if I am going down hill I would constantly get 9999 mpg

I loved that part!!! But on the other hand, I hated this part, climbiing hills/mountains it would show 3.5-3.8 mpg. Also with the SG II I found out my dash analog speedometer was 2 mph slow. I highly recommend the Scan Gauge II, it does alot. Also note I have a much larger coach (see sig.) than JC2 so I know this is all possible.

Don, any comments, you have the same coach.

Anyway, that's my 2 cents.......

David

bobpie · 08-01-2008, 05:38 PM

When we go away, if we are hot, I turn on hte dash air to get cool. If it isn't enough, I start the generator and put on the house air as a help. Once the coach gets cool we turn off the generator and run with the dash air. Oh, by the way, I turn on the defroster fans also. The driver MUST be comfortable, so I do just what I need. Temps from the vents- Dash air 45-50 degrees "F" from the foof vents 42- 54 degrees "F". That's just how it is. Thermometers in the vents.