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Old 07-26-2021, 10:37 PM   #1
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Denso dash A/C unit

Looking for help from our a/c guru's here. Had our Phaeton in for general service and asked for a/c service as my system is barely cooling. Per the techs note," recoverd 1.2 lbs of freon, vacuum test, no leaks. Recharged the system and pressure on high side at 400 and almost 0 on low side. ( work order does not say how much he put in) Condenser under the chassis looks clean and functioning. One of the lines going to the condenser was warm, the other was not. Believe it to be the expansion valve but cannot locate."
Any ideas on this guys diagnosis??

My brief google search has the expansion valve inside the evaporate case on this Denso unit. I cant imagine the pita its going to be to change that, half of it is in the dash area.

Idk, I think I want to get a second opinion on this before I let anyone tear my dash apart. Any thoughts from the guru's?
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Old 07-27-2021, 04:18 AM   #2
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Expansion valve

I hate to be the bearer of bad news, but according to the Denso Service manual it is in the the Evaporator box. I'm going thru something similar right now. I have a high pressure switch out. Its also in the box. Has to be removed to get to it. Go to Denso's site and download the Service manual. On page 45 you will see a dwg that shows an exploded view of what your looking for. I hope that helps.
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Old 07-27-2021, 12:34 PM   #3
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Have either of you guys tried replacing the receiver dryer? According to Bay Diesel & AC in Red Bay most system blockage problems are due to the receiver dryer screen being clogged. I would try replacing the receiver dryer first since it's easy to do and see what happens.
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Old 07-27-2021, 02:56 PM   #4
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Same

2015 Phaeton LH- Same problem, seems to be a blockage. Where is the dryer located?
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Old 07-27-2021, 03:01 PM   #5
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2015 Phaeton LH- Same problem, seems to be a blockage. Where is the dryer located?

It's up front by the evaporator housing. If you don't know what your doing it's best to let an AC professional change it out and refill the system with the CORRECT amount of R134a and run a leakage test.
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Old 07-27-2021, 03:31 PM   #6
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2015 Pheaton

Pulled system down it had 17 oz. in it Vacuumed system for 20 minutes system held for 10 minutes with no psi loss. Charged system to 32 oz. Low Side pressure was staying at 29 psi, high side around 175 psi. Compressor was still kicking on and off. Put 16 oz addition and low side psi dropped to zero high side was over 350 psi There is a blockage in the system.

Fan was kicking on up front away from condenser in unison with pressure numbers going up and down.
Just cant find schematic of system. Any idea where to find?
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Old 07-27-2021, 03:50 PM   #7
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Originally Posted by lllkrob View Post
Have either of you guys tried replacing the receiver dryer? According to Bay Diesel & AC in Red Bay most system blockage problems are due to the receiver dryer screen being clogged. I would try replacing the receiver dryer first since it's easy to do and see what happens.
Good advice. It would make sense to change that out as it looks easy to get to. Try the easy stuff first, right? I'm thinking the dryer should be replaced anyway even if I have to replace the expansion valve. Correct?
Anyone have a part number for the dryer? Mine was blasted by black paint from the factory and the tags are unreadable.

I see Tiffin list a part number at the online parts store. I assume that is a Tiffin bin part number and not the product number. But I dont know if that is the correct one anyway.
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Old 07-27-2021, 09:26 PM   #8
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Originally Posted by mrat240 View Post
Pulled system down it had 17 oz. in it Vacuumed system for 20 minutes system held for 10 minutes with no psi loss. Charged system to 32 oz. Low Side pressure was staying at 29 psi, high side around 175 psi. Compressor was still kicking on and off. Put 16 oz addition and low side psi dropped to zero high side was over 350 psi There is a blockage in the system.

Fan was kicking on up front away from condenser in unison with pressure numbers going up and down.
Just cant find schematic of system. Any idea where to find?

If you have 48 oz of R134a in your system you are WAY OVERCHARGED. That system only hold 2.1 lbs of R134a fully charged. You are running the risk of locking up the compressor. DID YOU REPLACE THE RECIEVER DRYER? Also you did not let set long enough under vacuum. It needs to set at full vacuum for at least 30 to 45 minutes to test for a leak.
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Old 07-27-2021, 09:45 PM   #9
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Props2.. see my long post.. in Fleetwood owners forums.. denso high pressure switch by Ledawg.. that will tell you the journey front to back.. it's a 13.00 part.. about 5,000.00 to replace.. no biggie if you got the bucks.. no real special tools or knowledge.. just someone with no 5,000.00 to burn on 13.00 part.. if your chassis or ford.. you can go to something like AutoZone and get dryers all day along for 3 less then using manufacturer part.. question... where do you think coach manufacturer gets them.. they don't make them.. they out sourced it.. there are only a few companies that actually makes them.. but what you do..is up to you.. I would like to know what you did.. and good luck..
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Old 07-27-2021, 09:53 PM   #10
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Where do you think the next shop that has your coach is going to look... on how to figure it out... boom.. ivr2.. print it off.. take it to them.. show them.. maybe if you show them.. they will give you 4,000.00 off.. really if you don't work on chassis.. don't do it... print off and see if shop will do it..ha,ha.. how much have they charged you so far.. to tell you your a/c system does not work? Something you already knew.. really tell us about how much it cost..? You don't have to be specific.. how much? Good luck let us know what you did and maybe better members then me will help you
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Old 07-28-2021, 05:40 AM   #11
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I just went through this, and actually still have an issue, on our 2014 Allegro Bus. We had a leak in the evaporator core. It is expensive if you have to have the dash pulled. I think it was 32 hours to R&R.

I suggest they do a dye test before you start replacing things.

When they replaced our dryer they just used one that worked. Didn't bother to use an exact OEM.
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Old 07-28-2021, 07:07 AM   #12
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Originally Posted by DRM901 View Post
I just went through this, and actually still have an issue, on our 2014 Allegro Bus. We had a leak in the evaporator core. It is expensive if you have to have the dash pulled. I think it was 32 hours to R&R.

I suggest they do a dye test before you start replacing things.

When they replaced our dryer they just used one that worked. Didn't bother to use an exact OEM.
Thanks for the heads up. Did Red Bay do your work?

In 2018, the system was pulled down and recharged with 2 lbs of 134a. They also added the dye.

The tech who just worked on the coach(different outfit) pulled the system down, found no leaks, but recovered 1.2 lbs. Hmmm
He then refilled the system. How much? I dont know, it was not in his notes. But he thought 2lbs seemed low to him for a refill. My friends "17" Phaeton has the factory sticker that says 2 1/2 lbs.(mine is gone)
My concern is the dude said the high side pressure is at 400. Did he overfill it? Did he remove some? Is 400psi way too high for this system? I dont know, I guess a phone call is in order.
I will take a physical measurement of the dryer and purchase locally. Tiffin's price for the dryer is way over the top(plus shipping) compared to what I see on line for similar dryers.
If the dryer does not fix the issue, then I guess its a drive to Red Bay. They would probably be the most efficient at tackling the job to replace the expansion valve. Shop prices here up north are just too high for people to be tearing things apart,who have no clue.
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Old 07-29-2021, 05:56 AM   #13
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I took it to NIRVC in Lewisville, TX. It took a while due to other work in the shop and parts shortage. I think the evaporator core was on backorder 6 weeks. They also replaced the 2 valves since they were easy to replace at that point.

It does sound like the 2nd shop may not be knowledgeable. Best of luck.
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Old 07-29-2021, 06:47 AM   #14
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Good advice. It would make sense to change that out as it looks easy to get to. Try the easy stuff first, right? I'm thinking the dryer should be replaced anyway even if I have to replace the expansion valve. Correct?
Anyone have a part number for the dryer? Mine was blasted by black paint from the factory and the tags are unreadable.

I see Tiffin list a part number at the online parts store. I assume that is a Tiffin bin part number and not the product number. But I dont know if that is the correct one anyway.
This is the part number for the dryer Tiffin replaced on my 2016 Bus,

5020351 AtR DRYER A/C pG 088566_
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