RV Trip Planning Discussions

Go Back   iRV2 Forums > THE OWNER'S CORNER FORUMS > Monaco Owner's Forum
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 06-06-2020, 05:05 PM   #1
Member
 
Join Date: Apr 2018
Posts: 40
Dash A/C not working - attempting to recharge, but high side is too high. Why?

Hi everyone,

The dash A/C quit working in my 2005 Monaco Signature 45' and I've been attempting to repair it. I've been learning a lot about A/C systems on the way but I'm a bit stumped. My coaches' manual calls for 4.0 lbs of R134A (64 oz). I have replaced both the air receiver-dryer and thermal expansion valve, and they're both located up front in the generator bay. I purchased a proper A/C vacuum pump and vacuumed the system for 3-4 hours. It remained in a >30 Hg vacuum for several hours indicating no big leaks.

After adding only 25 oz of R134A, the high side was up to 240 PSI with the low side being only 13 PSI. I tried to leave the system run for a bit, but the pressure only kept rising, and I finally shut it down when the high side creeped up close to 300 PSI. The A/C compressor clutch is correctly turning on and off depending on the mode selected on the A/C switch inside.

There is no sweating on any of the A/C lines up in the front generator bay. The dryer-receiver filter lines are hot to the touch, one of the expansion valve lines feel cool (not cold) while the rest are warm/hot.

I have tried to research the cause of a high pressure side being too high, and I can only find that there could be a blockage, but the expansion valve and receiver-dryers are typically the culprits, but they're both brand new.

Thanks for any insight that you can provide me!
__________________

__________________
2005 Monaco Signature Castle IV 45'
Hoss7 is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 06-06-2020, 05:43 PM   #2
Junior Member
 
Join Date: Mar 2019
Posts: 2
I had the same problem with mine. I found the module that controls the hyd. fan was not coming on to high speed to cool the condenser. Unplug the four wires to the module and the fan should go to high speed on default mode.
__________________

dmtaylor is offline   Reply With Quote
Old 06-06-2020, 06:29 PM   #3
Member
 
Join Date: Apr 2018
Posts: 40
Quote:
Originally Posted by dmtaylor View Post
I had the same problem with mine. I found the module that controls the hyd. fan was not coming on to high speed to cool the condenser. Unplug the four wires to the module and the fan should go to high speed on default mode.
That's interesting! Where is this hydraulic fan controller and what does it look like?
__________________
2005 Monaco Signature Castle IV 45'
Hoss7 is offline   Reply With Quote
Old 06-06-2020, 06:45 PM   #4
Member
 
Join Date: Apr 2014
Posts: 70
ac fan

Hi Hoss,
The condenser and fan (electric) is located right behind the front axle. There are 2 wires to the fan. I had a problem with mine and it was the ground wire not making a good connection. This fan will come on immediately when you turn the control knob to AC.
hope this helps, Jake
__________________
Jake & Starr Diede 2005 Signature Detroit 60 Series pushed by 2007 Lexus RX350
jakestarr is offline   Reply With Quote
Old 06-06-2020, 06:50 PM   #5
Member
 
Join Date: Apr 2018
Posts: 40
Quote:
Originally Posted by jakestarr View Post
Hi Hoss,
The condenser and fan (electric) is located right behind the front axle. There are 2 wires to the fan. I had a problem with mine and it was the ground wire not making a good connection. This fan will come on immediately when you turn the control knob to AC.
hope this helps, Jake
Thank you, Jake! I'll look to see if the fan is running or not when Max A/C is selected. If the fan isn't running, would this be causing the high side to have excessively high pressures like I'm experiencing?
__________________
2005 Monaco Signature Castle IV 45'
Hoss7 is offline   Reply With Quote
Old 06-06-2020, 06:53 PM   #6
Member
 
Join Date: Apr 2014
Posts: 70
ac fan

yes I believe so.
__________________
Jake & Starr Diede 2005 Signature Detroit 60 Series pushed by 2007 Lexus RX350
jakestarr is offline   Reply With Quote
Old 06-06-2020, 07:55 PM   #7
Senior Member
 
Isaac-1's Avatar
 
Join Date: Jun 2016
Location: SW Louisiana
Posts: 4,491
You might try spraying the condenser with a water hose to see if the high side pressure comes down, this will give you a clue as to the problem, if the fan is running and you are getting good airflow the condenser may be clogged (either internally or externally)
__________________
2002 Safari Trek 2830 on P32 Chassis with 8.1L
Isaac-1 is offline   Reply With Quote
Old 06-06-2020, 09:57 PM   #8
Senior Member
 
Join Date: May 2016
Posts: 172
Yes, not getting rid of the heat on the high side will absolutely push your head pressure up. You’ve received good advice. Make sure the fan is running to speed, and if necessary trickle water over the condenser to see if head pressure goes down. With no more charge than you have put in, you shouldn’t be seeing much heat on the high side line going to the dryer.

If the fan is up to speed, and trickling or spraying water on the condenser pulls the head pressure down, and you are able to add correct volume of refrigerant, system sweating back etc. then you would be looking for filthy/blocked condenser coils, or any other coil or obstruction in the air flow. If all this checks out and you still have trouble, let us know.

Other issues can cause too much pressure but you have addressed the most probably causes by evacuating the system, and replacing the Expansion valve and dryer.
__________________
Marvin (and Eileen) - Weekend RVer On A Budget
1997 34’ Gas Bounder / F53 Chassis | Towing 2007 Taurus on Acme Dolly
MarvinG is offline   Reply With Quote
Old 06-07-2020, 03:47 AM   #9
Member
 
Join Date: Mar 2019
Posts: 51
What was the initial problem with the system that you had to change the expansion valve?
Cj D is offline   Reply With Quote
Old 06-07-2020, 05:09 AM   #10
Senior Member
 
Monaco Owners Club
Join Date: Sep 2013
Posts: 1,850
Quote:
Originally Posted by jakestarr View Post
Hi Hoss,
The condenser and fan (electric) is located right behind the front axle. There are 2 wires to the fan. I had a problem with mine and it was the ground wire not making a good connection. This fan will come on immediately when you turn the control knob to AC.
hope this helps, Jake
I also assume your condenser is up front behind the axle, one speed & it has to run to keep the pressure down. When you turn the A/C on it should turn on as jakestar says.
__________________
2007 Monaco Signature Noble III 45' ISX 600HP
hypoxia is online now   Reply With Quote
Old 06-07-2020, 10:27 AM   #11
Junior Member
 
Join Date: Mar 2019
Posts: 2
in the engine compartment , close to the fan . follow the wires from the fan to the module
dmtaylor is offline   Reply With Quote
Old 06-07-2020, 10:40 AM   #12
Senior Member
 
Monaco Owners Club
Join Date: Sep 2013
Posts: 1,850
Quote:
Originally Posted by dmtaylor View Post
in the engine compartment , close to the fan . follow the wires from the fan to the module
Not a factor on his coach since the condenser is not associated with the hydraulic fan and is at the front axle.
__________________
2007 Monaco Signature Noble III 45' ISX 600HP
hypoxia is online now   Reply With Quote
Old 06-07-2020, 06:03 PM   #13
Member
 
Join Date: Apr 2018
Posts: 40
The amount of knowledgeable people in this forum always completely surprises me! Thank you so much to everyone who helped - it was indeed the condenser fan, located behind the front axle. As soon as I touched the wires, the fan turned on; I unplugged it and thoroughly sprayed the connectors with electronic connector cleaner, firmly plugged them back together and it seems to be working fine no matter which way I wiggle or twist the wires.

I have successfully recharged the system with a hair under 72 oz. I accounted for 2 oz lost in the service lines, and 1 oz lost per can used (purging the service lines after connecting each can, etc), which should have yielded just about 64 oz (rated system capacity). The high side was 175 PSI, with the low side being 13 PSI at idle. Outside temperatures were 74°, and temperatures measured 1" from condenser coils underneath the coach was 90°. The Monaco manual called for 198 PSI on the high side when 1" from the condenser coils were 90°, but I didn't want to overcharge the system as the manual didn't specify whether that is considered at idle, or at a raised idle. Raising the engine speed from idle (600 RPM) to 1000 RPM, the high side increased to 197 PSI and the low side decreased to 10 PSI.

Is it normal for the low side to be so low on these coaches? With the ambient (inside RV) temps of 73°, the vent temps were 50° on Max A/C.

Would I see a noticeable decrease of vent temps if I were to clean and spray down the condenser coils and evaporator coils? It's DIRTY underneath that coach!

Thanks again for everyone's help!
__________________
2005 Monaco Signature Castle IV 45'
Hoss7 is offline   Reply With Quote
Old 06-07-2020, 09:36 PM   #14
Senior Member
 
Join Date: May 2016
Posts: 172
Rule of thumb: 20 degree drop is generally considered good. Your low side pressure seems a bit low, assuming R134. (I don’t have a refrigerant chart in front of me.) I would not charge more than the manufacturer states is the correct charge however. You can have too low pressure on the low side for the same reason as you had too high on the high side: not enough air going across the coil, if the evap coil is dirty, cleaning it would increase air flow and raise the low side pressure.

Other things causing too low a pressure: obstruction (but you replaced the txv) low charge (but you added the specified amount). I personally wouldn’t get overly worried about low side pressure as long as I have good air flow, and as long as the evaporator doesn’t freeze up with prolonged use.
__________________

__________________
Marvin (and Eileen) - Weekend RVer On A Budget
1997 34’ Gas Bounder / F53 Chassis | Towing 2007 Taurus on Acme Dolly
MarvinG is offline   Reply With Quote
Reply

Tags
dash



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Too high / too low / too high RTegarini Allison Transmission Forum 15 06-25-2018 06:30 PM
Attempting to raise the painted grill at side radiator wagonmaster2 Newmar Owner's Forum 16 07-06-2017 04:04 AM
Attempting to un-freeze credit reports wagonmaster2 Just Conversation 15 01-26-2015 08:39 PM
Onan Diesel Generator won't turn over when attempting start michguy RV Systems & Appliances 11 03-06-2013 03:52 PM
House Batteries Not Charging - Appears Converter Not Working - But Don't See Why? vsheetz RV Systems & Appliances 12 01-21-2013 07:50 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 02:34 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×