AC dryer and expansion valve

[Guest timkuhler]

I need help in finding a AC dryer and expansion valve for my 2008 Holiday Rambler Scepter.  I have the red engine, ISL400.  I have found the Sanden 4420 compressor, but need to find the correct dryer and expansion valve before I tear into it.  Any help is appreciated. Thanks Tim Kuhler. Tkdk@hctc.net

[Hypoxia]

Possibly dryer and expansion valve 

UAC Parts

Edited September 17, 2021 by Hypoxia

[redeye0315]

On my 2003 scepter, the drier is located above the rear differential. Right in front of differential, bolted to the underside of the floor. It high up in there and difficult to reach. I actually need to change mine but haven’t figured out how to access it. The expansion valve is located in the front next to the service ports wrapped in rubberized insulation tape 

[timaz996]

If you were asking where they are located on your coach they should be upfront. Open your compartment for where the generator is at and look in there.If you were asking where they are located on your coach they should be upfront. Open your compartment for where the generator is at and look in there.

Tim

[Guest Ray Davis]

39 minutes ago, redeye0315 said:

On my 2003 scepter, the drier is located above the rear differential. Right in front of differential, bolted to the underside of the floor. It high up in there and difficult to reach. I actually need to change mine but haven’t figured out how to access it. The expansion valve is located in the front next to the service ports wrapped in rubberized insulation tape 

That's exactly like my 03 Windsor.   I managed to sit up in a space under there and change my dryer.  Took it and expansion valve to my local Parts Plus and they had both of them

I think I can see the dryer from my bedroom hatch,  might even be able to replace it from there.

[ekgflashnet]

Ray,

Can you tell me where you found your A/C expansion valve?  I have a 2005 dynasty.  I see the A/C drier (round black cylinder shaped cannister).  I see two A/C lines running into the large black box which houses the A/C evaporator core (small radiator heat exchanger).  But, I don't know where to look for the expansion valve.  I believe mine is stuck in the open position.  Is it an in-line fitting or do both the high and low pressure lines connect to the expansion valve.

 

thanks,

steveg 2005 DDIV

[Ivan K]

Hopefully yours isn't where ours is but just in case, here's a pic of what it looks like. 

[Guest Ray Davis]

Steve, sorry I didn't get back yesterday.  We had about 30 family members here for our Easter egg hunt and lunch, so I didn't even look at my computer.                                                                                                                                                                                                                               

I see now that you got an answer in a new thread.  

What makes you think the valve is stuck open?

 

Ivan, thanks for posting a picture of your expansion valve.  I did not know any Monacos had that sort of HVAC and expansion valve.   ekgflashnet's valve isn't like yours though, his is a round valve on the firewall as pictured in the next thread he started after this thread.

Edited April 18, 2022 by Ray Davis

[ekgflashnet]

When I measured the pressure on the low side at the compressor, it pegged out at more than 100 psi (and the compressor would not engage).  This would seem to indicate an open expansion valve.  However, after coming home and measuring it again, it was at a normal 35 psi.  I'm thinking the expansion valve is starting to fail.

steveg 2005 ddiv

[Guest Ray Davis]

3 hours ago, ekgflashnet said:

When I measured the pressure on the low side at the compressor, it pegged out at more than 100 psi (and the compressor would not engage).  This would seem to indicate an open expansion valve.  However, after coming home and measuring it again, it was at a normal 35 psi.  I'm thinking the expansion valve is starting to fail.

steveg 2005 ddiv

Hmm, I'm not an A/C expert but it seems like we need to think this through. 100 psi, compressor not turning doesn't point to the expansion valve I don't believe.  If the compressor is not turning the exp valve is not even in play, 100 psi is probably the at rest pressure.  It's probably still 100 psi when the engine is off.  Now, when the pressure was at 35 psi was the compressor turning, and if so, was it cooling?  It appears to me that you may have an intermittent electrical issue of the compressor not turning on.  I would not open the system until you are sure the valve is bad.

Edited April 19, 2022 by Ray Davis

[ekgflashnet]

Here's what I'm thinking may have occurred.  The compressor was running normally when the expansion valve got stuck in the open position.  This let the high pressure bleed into the low pressure line.  The safety switch (trinary switch) caught this and shutdown the compressor.  I'm not sure, but when this happened, there was no where for the high pressure to bleed off.  We noticed the problem while travelling when the A/C was no longer cooling.  That is why I checked the pressure to see if there was sufficient freon.  I've read that one of the symptoms of an expansion valve failure in the open position is to allow the high pressure to pass thru the expansion valve.  I'm open to other explanations. I'm thinking that during normal operation when the compressor stops,  the expansion valve will fully close.  Leaving high pressure on the high side. When I returned home and checked again, the pressure was at 35 psi, the compressor was running, the air was cooling and the trinary switch was closed (i.e. passing 12v to the compressor).  I did not check the trinary switch when I measured the 100 psi reading, but I assume it was open causing the compressor to stop.

 

steveg 2005 DDIV

[Hypoxia]

What was the high side pressure?

[ekgflashnet]

I did not measure this.  Also, I don't have a high pressure gauge.  So, no info I can supply.

steveg 2005 DDIV

[David Pratt]

The purpose of the Expansion Valve in the A/C System is to convert the Freon from a Liquid to a Gas going into the Evaporator. The Expansion Valve is always positioned on the High Pressure side of the A/C system between the Compressor and the Evaporator. It is very rare for an Expansion Valve to stick open as they are normally open and only close to meter the amount of Freon going into the Evaporator that is converted to gas for cooling and is controlled by temperature. There is also the Receiver/Drier that is located on the high side of the system before the Condenser to filter any moisture or debris out of the system. If there is contaminates in the A/c System it may plug up the Expansion Valve causing higher than normal pressure readings. A contaminated Receiver/Drier will also cause higher than normal pressures.

The pressure you are reading on the low side of the system when the Compressor is not running is called the Vapor Pressure. When the A/C System is properly filled the Vapor Pressure (some Techs will also call it Static Pressure) will fluctuate up and down based on the outside air temperature, normally between 80 to 120 PSI. If you have a leak in the A/C system the Vapor Pressure will go down as the Freon leaks out until there is no Liquid Freon left. When the Vapor Pressure goes below 50psi the system is out of Freon.

When the A/C system is turned on and the Compressor is running, the Low side pressure should read between 30psi to 40psi and the high side pressure around 312psi to 390psi. These pressure are all regulated by the outside air temp. The higher the OAT the higher the A/C system pressure will elevate and fluctuate. The Pressure Switch will cut the Compressor off when the pressure on the low side goes below 28psi or the high side goes above 398psi

If your system pressures are in range, another check you should do is to check the temperature of the air coming out of the A/C vents in the dash. To properly check that temperature, turn the A/C system on to MAX (Recirculate), and Fan on high speed. You should take the temperature from the closest  vent coming from the Evaporator. That temperature will fluctuate up and down depending on what the OAT is. On a 75 degree day you should see temperatures in the low to mid 40's and a low side pressure between 25 to 32 psi..

You can Google for charts that will show you what pressures and temps your system should operate with the different outside air temps.

[ekgflashnet]

Thanks for the great explanation. So, based upon your description, what I was seeing was normal when the compressor is not running.  So, that seems to now remove the expansion valve from the list of possible issues.  The question now is why is the compressor sometimes not running when the A/C is turned on (Max AC settin).  I did notice that the A/C line running into the drier has been previously pinched (or crushed).  Perhaps this is the problem that the flow is being limited by the damage to this line.  Here's a picture of that damage.

 

thanks for your feedback/suggestions,

steveg 2005 DDIV

[David Pratt]

That hose appears to be a #6 A/C hose which would be the high pressure side of the system. I would doubt that dent would cause your problem. You should put a set of gauges on the system so you can see what the high and low side pressures are when the A/C is running, That will tell you more than trying to guess what is going on.

Another check you should do is to make sure the Condenser Fan is running when the Compressor is running. The A/C system is set up so that when ever the Compressor is running the Condenser Fan will be running. If the Condenser Fan is not running when the Compressor is running then the pressure on the high side will rise above the high pressure cutoff point of the pressure switch and shut the Compressor off. When the pressure bleeds off back to the normal operating pressure the compressor will come back on.

Another issue could be you may have a Receiver/Drier Failing. A set of gauges hooked up to the system to monitor pressures is the only way to trouble shoot the issue your are having if it is a pressure related issue and not an electrical issue.

[ekgflashnet]

Dave,

I went ahead and rented some gauges from AutoZone (basically free if you return it like you got it).  Here' some readings I found:

Engine Off, compressor off, low side 82 psi, high side 70 psi
Engine on, compressor off, 82/70 (same as you would expect)
Engine on, compressor on, 30 psi, 175 psi.  I however noticed, that the longer I ran the compressor, the higher the pressure went on the high side
5 minutes later, 26 psi/225 psi
10 minutes later, 27 psi/250psi
15 minutes later, 29/275
20 minutes later, 30/300
25 minutes later, 32/310.  I believe that after a longer time of operation, the system may eventually shut the compressor off if the pressures keep going too high.

Based upon what I've read these readings indicate either too much air in the system or too much moisture.  I recently had the A/C evacuated and charged, so it should not be too much air.  Like you pointed above though, perhaps this is pointing to a drier failure.  At least that is an easy replacement.  What's your take given these readings?

steveg 2005 DDIV

[Hypoxia]

20 minutes ago, ekgflashnet said:

 

Was the condenser fan running?  Do the pressures drop when you use a hose & run water through the condenser?  Is the condenser clean & if the fan is running, does it sound like it is running at a high speed or is it perhaps slow?

[Guest Ray Davis]

Pressures depend on outside temp, sufficient air over the condenser, air inside over the evaporator and engine speed. 

On most Monacoes the condenser is cooled by the engine fan, however some use an electric fan.  Do you know if yours has an elect condenser fan?

Here is a chart that may help.  Depending on the ambient/outside temp, your pressures may not be that far off.

 

[ekgflashnet]

the ambient temperature when doing my tests were around 75 to 80 degrees.  My coach has a side radiator where the condenser is located which is cooled by the engine fan.  My high side reading seems high for the ambient temperature I was at.

 

steveg 2005 ddiv

[Guest Ray Davis]

3 hours ago, ekgflashnet said:

My high side reading seems high for the ambient temperature I was at.

Yeah, they do both seem off a little.   Did you have the RPMs up?   Around 1200 on fast idle.   You have 2 pipes going to the evaporator, the small one ( with the dents )  and a larger one ( return low pressure ) this larger one should be cold and sweating.  

A few yrs ago I had a similar problem to you and I did replace the expansion valve and drier.  I have not checked my pressures since then because it cools fine now.        However, I have added a little R134 using a Walmart gauge until it was in the green again.   I took the expansion valve and drier into my local Parts Plus store where they  matched them up, mine were just parts for auto air conditioners.

[David Pratt]

Steve

Are you sure that the A/C condenser is located in front of the side Radiator on your coach. On most 05-07 RR10RS Chassis Coaches, the Condenser was located under the coach behind the Generator and had an Electric fan attached to the front of it that ran when the compressor was running. I am not sure where the Condenser fan was located on the early Dynasty's. If my memory serves me right I know the condenser was installed in front of the radiator, outside on the lower side around 08.

You need to operate the A/C System until all the pressures stabilize and measure the Temperature at the Center Vents with the System in re-circulate and fan on high. With the OAT between 75-80 degree's the outlet temp at the vent should be in the low to mid 40's when the pressures have stabilized.

At that OAT your Low side Temp of 32psi is in the normal range, but your high side should be in the 175-225 psi range and the vent temperature at the dash in the 40's

If you had a blockage in the system both the low and high side pressures would be high not just the high side.

The Pressure Switch will cut the Compressor off when the High Side Pressure reaches around 398psi and will turn the Compressor back on when the pressure bleeds off to around 310psi.

All the information you have posted indicates you may not be getting enough airflow over the condenser which will cause the High Pressure reading on the High Side. You need to confirm all the above to be able to further diagnose what is going on.

You need to let the A/C System run until all the pressure's stabilize and until the compressor shuts down and see what your maximum pressures are and the vent temperature is.

[ekgflashnet]

Dave, thanks for the continued responses.  I know for sure I don't have a condenser and electric fan up front near the generator.  I did assume the condenser is on the side radiator (I haven't actually traced the high side hose from the compressor to what looks like the condenser on the side radiator).  Since the failure of the compressor to engage is not really repeatable, I'll have to try to perform further tests the next time it does occur. 

steveg 2005 DDIV

[TommyL]

Steve  another way to check correct volume of Freon. I let my unit set overnight to let the Freon equalize. High and low will be same psi. Put a thermometer next to Freon hose,your trying to get the temp of the Freon ,read temp and pressure at  arkema .com chart. Match your temp to chart ,if you’re psi. Is close at least Freon volume isn’t your problem.This works wether you have a 2or 10 lb system.I’m just a do it yourselfer  so take it for what it’s worth .TommyL 

[Woody O]

On 9/17/2021 at 12:51 PM, timkuhler said:

I need help in finding a AC dryer and expansion valve for my 2008 Holiday Rambler Scepter.  I have the red engine, ISL400.  I have found the Sanden 4420 compressor, but need to find the correct dryer and expansion valve before I tear into it.  Any help is appreciated. Thanks Tim Kuhler. Tkdk@hctc.net

Did you find everything and did you solve your cooling problem? If so, what was the solution?