Completely redid A/C system on my E150 about 2 weeks ago, charged, and had cold air at the front and rear vents. Awesome

Fast foreward a few days ago I kick on the A/C and nothing in the rear vents. Front vents still blowing ice cold. Made sure coolant wasn’t flowing back there making warm air, it wasn’t.
Rear evaporator not cold at all, the expansion valve and lines going to it were pretty cold but not too cold.
Mind you, to repair the rear, I had custom rubber lines made, so I made sure those weren’t leaking. I found one what seems like a very small leak on a spring connection that does go to the rear, but it seems very small. Also I checked my high and low pressures with gauges and everything read the right pressures for that days temps.

With all that being said, I’m thinking clogged rear expansion valve or the small leak, or both. Unfortunately looks like I’ll have to evacuate refrigerant and fix these. But if anyone has other ideas or insight, it’s appreciated.

 

Following as I have my own rear issues on my 89 e350 5.8 elsewhere. Did you do the repairs yourself or a shop? WHere do you live by chance.

John V
Miami FL

 

yes I did everything myself here in northern NJ. Do you have the same type of issues?

 

My HVAC friend used to talk about the rear issue dealing with drain back, the system need be mounted higher than the compressor in a long run, only ever seen those in Generl Motors, they put their unit over the back doors.

 

Damn, that’d be ****ty if that’s what it really was. I am almost to the point of just running it how it is. I’m several hundred dollars in and a lot of hours. But tbh on hot days that rear ac unit would be realllyyy nice

 

I think he has a hightop 80's Econoline still, he put dual fans on his oversized condenser up front, I know its bigger than mine, don't know what else he did, its been years since I've been able to hang out with them, we had 300 custom vans come out to the 2005 Nationals, I sat with him and a few other guys in a barn and talked vans. There was a guy who put a house 110 ac under his bed in the rear, cut holes to allow in air, refused to believe when told the heat would collect under the van making it impossible to exchange the heat inside, it was for use when stationary plugged into a power pole, think he gave up. Mercedes had a roof mounted unit on their large vans that were later converted to an RV, I believe the unit tied into the compressor on the engine tho, not sure you'll find one used, I don't cut holes in the roof of vehicles, it never ends well. I spent a lot trying to cool my Dodge Dakota, practically rebuilt the entire AC system, when stopped in traffic it went from cold to warm, pretty sure electric fans up front could have corrected that, what you have is more fluid passing in the front, or perhaps faster than the rear, wonder if they put a screen filter separate on the line to the rear?
The old vans practically gotta be torn completely apart and have all the components updated to the new stuff to work optimum, and it ain't cheap, seen 2 guys do it to their 70's Dodge vans, they did not put a rear unit in because the HVAC guy in the club said it just causes problems.

 

Ya, didn’t want to do the roof mount thing, screw cutting holes. But ya, every component is new besides the rear evaporator, but I flushed the **** out of it. Like 3 or 4 times. It’s just weird that it worked for a little bit at first. Still deciding what I’m gonna do. But im leaning towards tearing it back apart and recharging, I’ve come this far, I wanna do it right.

 

Ford has used this rear expansion valve for about 40 years now
If your pressures are good and the front blows cool, this expansion valve is most likely the fault
Generally, it's a pretty robust part
But
I've had to replace a few over the years
Some of the older ones were a capillary tube included with a new evaporator
Yours should be this style
Possibly you added a bunch of A/C oil?
Means
Maybe it's just plugged up and will come out of it after some drive time at 2500 rpm
The old equalize the pressures thing by running it at 2500 rpm for 2 minutes
I'd do that several times before sucking it down, (evacuating the freon) and replacing the expansion valve
​​​​​​​

 

yes that’s it. I used one off rock auto that was a little different than the original though.

 

Actually, it’s possible it got over oiled a little bit. So what, you’re saying maybe let it run for a little and see if it unclogs? I do have a warm day coming up to try that.

 

Yes, i would do the pressure equalizing procedure and run it for a while before tearing back into it

 

Ok I’ll give that a shot. I drove it around a little bit but not too long after it happened, but the A/C hasn’t been on in a week or 2. You recommend doing it idoling or on a drive? Or take pressures at 2500 rpm ?

 

I'd actually drive it for 10-20 miles
The book always said to run them at 2500 rpm for 2 minutes to equalize the pressures
If you have too much oil in a fixed orifice or the expansion valve, it'll take longer than that
How a pro does it (like me) is have your recycler handy and momentarily shoot some freon into your recycler and see how much oil shoots out with the initial stream of freon exiting the system
If you are heavy on the oil, you'll need to remove some
A recycler is the about the only legal way to remove some oil
They can run rich with oil (polluted with oil)
The oil rich refrigerant can still function, system performance just might be down a few degrees
I see it a lot, you go to hook up a gauge set and you get oil out when connecting the gauge set

 

Ok got some updates. Drove it 2 hours home from camping and it was 75 degrees. Front still blows ice cold, nothing at rear. But the compressor started short cycling after 10 minutes. If I shut it off for a while and turn it back on, runs fine for a few then short cycles once in a while. Weird. Almost liek once it equalizes pressure, it short cycles?
So I have a very small leak at one of the rear lines. Obv gonna address this first. I think I’m just gonna put more 134 in after and see what happens and go from there

 

Short cycle time is an indication of low on freon
Sounds like the pressures are equalized now
You want to fix any leaks, then evacuate and recharge with the exact right amount of freon
Your underhood sticker will have the refrigerant charge required (and how much oil)