OK gang, This is for you EXERTS that know air conditioning and, all aspects of it. Below is a picture of the A/C condenser and, the electric fan that provides air for cooling of it. You'll see that the fan, has NO SHROUD (that is of value). Now, in most, if not all, radiator situations, on just about every car, truck, air plane, space ship etc. that have ever been built, there is a real shroud that encompasses the entire radiator fin area and, it's also usually very close to the tips of the fan blades. All that means that, the fan can pull (or possibly push) air through the fins, ALL THE FINS, making the cooling effects much more efficient, than what I think is going on in the picture below. In reality, if you look at the picture closely, it appears that I may have as much as 25-30% of that condenser that it not actively having air forced through it, due the fact that there's no real shroud involved. Our coach, an '04 Itasca Horizon 36GD with the C-7 330HP CAT, has basement air conditioning style on the passenger side rear compartment and, the dash air system on the same rear compartment, on the drivers side. The dash air conditioning system does work and, it works just OK. I just had it evacked (is that a word?)and re-charged. The folks that did the work stated that there is no leaks. So, I'm wondering, does anyone think that, it would be worth the effort to somehow, fabricate up, a shroud that would encompass ALL the fins in that condenser? Does anyone think that, it would improve the efficiency and therefor, the cooling process of the R-134A in that system. And therefore, if your efficiency is improved, it should, I SAY SHOULD.....POSSIBLY.... get us colder air, emanating from the dash A/C ducts????? Scott

It appears the fan blade tips have a small shroud. I rarely have to run my roof airs and here are the things I've done to mine to make it work very well, even doing the second part: Make sure your heater valve is shutting all of the hot water off... even adding a manual valve up front. Pull the cap tube most of the way our of the evaporator... even putting a fuse in the plug for it so the compressor runs all of the time.On a previous MH I added a set of misters in front of the condenser fan so when I turned on the water pump it helped cool the condenser which in AZ would work very well.Ebay $30 and I would do these three things before building a shroud.You could also add a pair of rear window rain guards to your grill to force air in... one at each edge of the fan.

Scott, what I see is that it does have a Small one. Turn it off and you will notice how much it is cooling. The spot cooling does more than one thinks. I did what you are thanking many years ago and what I got in return was no many degrees drop for what I spent to try to get it better. Back in the 60/70s you could get a mister that sprayed a mist and cool down some. The draw back was rusty nuts if you did not get them adjusted correct.

Is the radiator and engine driven radiator fan mounted in front of that condenser? If so no I wouldn't recommend any shroud as it would just help to block cooling airflow.

The problem is I don't think you have the room to build a real shroud unless there is room on the backside to do it. I haven't looked at mine in awhile.

You do not need a shroud, once you are moving the fan probably turns off on temperature anyway. Electric fans are normally used for when you idle or are moving slow in traffic on a hot day, thermostatically controlled. It is possible to cool a condenser too much, not creating enough high side pressure to properly feed the TXV or metering device there by reducing capacity. Unless you travel everywhere at 20 MPH or less its probably good the way it is.

OK, question for you "A/C" experts | Good Sam Community

13 Replies

FIRE_UP
Explorer
Jul 29, 2015
BobR wrote:
I think your idea has merit. Your past posting of projects you've done leads me to believe you could easily fab a shroud from sheet metal and test it out. If it does improve cooling, then you could refine it (make pretty).

BobR,
I most certainly thank you for your nice comment on my capabilities. When winter comes around, I think I'll just do that. I'll goof around with some sheet metal or maybe even some sheet plastic. I mean what the heck, I got the time so, why not?
Scott
BobR
Explorer
Jul 25, 2015
I think your idea has merit. Your past posting of projects you've done leads me to believe you could easily fab a shroud from sheet metal and test it out. If it does improve cooling, then you could refine it (make pretty).
FIRE_UP
Explorer
Jul 25, 2015
Bikeboy57 wrote:
Let's quantify the situation to see if you have a problem or not. How cold is the air coming from the ducts? With 134a, you can get air about 30 degrees cooler than ambient. You can use a digital kitchen thermometer to take a reading.

Next question would be what do the gauges say on hi and lo pressures at high idle. Please give the ambient air temp and relative humidity.

Well Sir,
I have one of those thermometers that you stick in the vent to check the air temp as the A/C is on and, in the high position. I will check that. I should have before posting this so I'd have more accurate info for any of you to ponder over while trying to help me on this issue. It's in the barn (old term us firemen used for when the fire truck was parked at home) right now so, I'll have to move it out to run the big CAT and check that A/C duct temp.
As I recall, if working correctly, most A/C units will drop the temp of an area (in this case, we're talking the cab of a coach) at least 20 degrees down from the ambient temp.

So, in our case, our outside temps at this time of the season, play around at 105 or so. So, that means that, that system should, I say SHOULD drop the inside air to around, 85 or so degrees. I'm no expert on any of this, just trying to remember what I was told a long time ago.
Scott
Bikeboy57
Explorer
Jul 25, 2015
Let's quantify the situation to see if you have a problem or not. How cold is the air coming from the ducts? With 134a, you can get air about 30 degrees cooler than ambient. You can use a digital kitchen thermometer to take a reading.

Next question would be what do the gauges say on hi and lo pressures at high idle. Please give the ambient air temp and relative humidity.
jyrostng
Explorer
Jul 25, 2015
as I see it, the real question is, "how hot is the line that exits the condenser when the fan is running"? If that fan isn't able to remove the heat from the 134A then it can't absorb as much heat from the inside air and the inside air won't be as cool.

on a side note, spraying water on a condenser coil will result in the minerals in the water being deposited on the coil and eventually it becomes like concrete. The water evaporates and helps cool the coil but the minerals in the water stay.

There are a lot of after market radiator cooling electric fans, some with dual fans, you may find one that covers the whole area of that condensers rectangle. something like this http://www.carid.com/dorman/radiator-fan-assembly-mpn-620-616.html?gclid=CjwKEAjwxMetBRDJx6Sz2p7DsQ0SJADJHAqNZ8pp7HkvaiqSOpXBRJH9WqkQvtXYE25Q9iEnA-4nOBoCZkzw_wcB

all of these also have shrouds if you have room for one http://www.summitracing.com/search/brand/derale-cooling-products/product-line/derale-performance-high-output-dual-rad-fan-and-shroud-kits
JetAonly
Explorer
Jul 21, 2015
Like Ivylog said, my heater valve will corrode on the electrical connections and add hot water when not selected.

There are many choices of electric fans, up to 10k CFM. The shrouding for the one you have is in the mount, venturi effect will draw in a significant amount of air around it.

My dash AC will nearly blow ice cubes, it produces frost at the expansion valve. I would also check the ducting in the dash unit. Perhaps an internal baffle is not operating correctly, stuck open or closed.
Executive45
Explorer III
Jul 21, 2015
FIRE UP wrote:
First off,
I sure want to thank you all for trying to assist in my thoughts here./snip/
Chuck,
I have no way of telling if that fan shuts down while we're in motion with the coach, and the dash A/C is on. I'm no expert on that particular A/C unit and it's total operation but, I suspect that, that fan doesn't shut off at any time, while the A/C is in the "ON" position and, we're using it. The reason I state this is, by logic, and that fluid (R-134A) being pumped through that condenser in a heated stage, it would have to be constantly cooled by that fan. And, being on the SIDE of that coach, there's not much "forced" air through that condenser.

So again, thank you all for your assistance here. It's very much appreciated.
Scott

Time for a GoPro and a drive down the fwy....:W....Dennis
FIRE_UP
Explorer
Jul 21, 2015
First off,
I sure want to thank you all for trying to assist in my thoughts here.

"Is the radiator and engine driven radiator fan mounted in front of that condenser? If so no I wouldn't recommend any shroud as it would just help to block cooling airflow."

No Sir, as stated, this is a diesel pusher coach. The engine fan, (constant drive, no fan clutch) the CAC and, the radiator are at the rear of the coach. The fan and A/C condenser that you see in the picture, are on the drivers side of the coach, approximately 2+ feet from the side of the engine block.

"The problem is I don't think you have the room to build a real shroud unless there is room on the backside to do it. I haven't looked at mine in awhile."

Hey Jeff, thanks for your input. You could be right. There is not all that much room between the face of that condenser and, the back side of the painted compartment door. But, BUT, I've seen many fans and shrouds that are fairly thin and still get the job of channeling air done. We'll see.

"You do not need a shroud, once you are moving the fan probably turns off on temperature anyway. Electric fans are normally used for when you idle or are moving slow in traffic on a hot day, thermostatically controlled. It is possible to cool a condenser too much, not creating enough high side pressure to properly feed the TXV or metering device there by reducing capacity.
Unless you travel everywhere at 20 MPH or less its probably good the way it is. "

Chuck,
I have no way of telling if that fan shuts down while we're in motion with the coach, and the dash A/C is on. I'm no expert on that particular A/C unit and it's total operation but, I suspect that, that fan doesn't shut off at any time, while the A/C is in the "ON" position and, we're using it. The reason I state this is, by logic, and that fluid (R-134A) being pumped through that condenser in a heated stage, it would have to be constantly cooled by that fan. And, being on the SIDE of that coach, there's not much "forced" air through that condenser.

So again, thank you all for your assistance here. It's very much appreciated.
Scott
chuckftboy
Explorer
Jul 21, 2015
You do not need a shroud, once you are moving the fan probably turns off on temperature anyway. Electric fans are normally used for when you idle or are moving slow in traffic on a hot day, thermostatically controlled. It is possible to cool a condenser too much, not creating enough high side pressure to properly feed the TXV or metering device there by reducing capacity.
Unless you travel everywhere at 20 MPH or less its probably good the way it is.
SCVJeff
Explorer
Jul 21, 2015
The problem is I don't think you have the room to build a real shroud unless there is room on the backside to do it. I haven't looked at mine in awhile.