Troubleshoot front ac periodically warm?

[bigjoncoop]

2007 EXPLORER XLT V6 4.0
ISSUE: Front AC intermittently Blows warm while rear AC ice cold. Blend door is permanently jammed to the cold side, so it's definitely not the blend door...

System pressure is spot on! Low side = 40 / High side = 210-215 (Recently had the system evacuated. Then pulled a vacuum on it for about 45 minutes, and refilled)

System has been working perfect until last week when I noticed that the front was blowing semi-warm once in awhile. The rear continues to work fine.

I found that when it's blowing warm, if I turn the front blower down / off for a minute or 2 then back on its ice cold again for a few moments. It seems as if there is not enough refrigerant flowing through the evaporator to keep up if the blower is on high.

The front does continue to blow cold most of the time until it has this issue intermittently...

I'm hoping this is something I can fix without having to tear you there for a part to get to the evaporator etc... if that's the case I'll just live with it..

 

[fixmiester]

2007 EXPLORER XLT V6 4.0
ISSUE: Front AC intermittently Blows warm while rear AC ice cold. Blend door is permanently jammed to the cold side, so it's definitely not the blend door...

System pressure is spot on! Low side = 40 / High side = 210-215 (Recently had the system evacuated. Then pulled a vacuum on it for about 45 minutes, and refilled)

System has been working perfect until last week when I noticed that the front was blowing semi-warm once in awhile. The rear continues to work fine.

I found that when it's blowing warm, if I turn the front blower down / off for a minute or 2 then back on its ice cold again for a few moments. It seems as if there is not enough refrigerant flowing through the evaporator to keep up if the blower is on high.

The front does continue to blow cold most of the time until it has this issue intermittently...

I'm hoping this is something I can fix without having to tear you there for a part to get to the evaporator etc... if that's the case I'll just live with it..

I've had similar problem on my 4.6 L and it is related to a leak in a vacuum accumulator that shuts off the hot water going into the heater. Almost always happens during heavy acceleration, when the manifold vacuum is low, and the accumulator is supposed to keep the heater valve closed, until the manifold vacuum recovers. It's not a blend door issue, as far as I can tell. It's the heater core suddenly warming up until the valve again closes. I've tried sealing up the vacuum lines to the accumulator, but there may be a bad check valve intermittently leaking. Not a big problem so far.

 

[bigjoncoop]

I've had similar problem on my 4.6 L and it is related to a leak in a vacuum accumulator that shuts off the hot water going into the heater. Almost always happens during heavy acceleration, when the manifold vacuum is low, and the accumulator is supposed to keep the heater valve closed, until the manifold vacuum recovers. It's not a blend door issue, as far as I can tell. It's the heater core suddenly warming up until the valve again closes. I've tried sealing up the vacuum lines to the accumulator, but there may be a bad check valve intermittently leaking. Not a big problem so far.

Hey thanks for replay, sorry it's been so long...

I can say for sure thats not my issue, since I had bypassed the heater core a long time ago. Also as I mentioned, it's also definitely not the blend door neither since I have it jammed permanently open to the cold side.

This problem has now started to become consistent and happening constantly. AC pressures are spot on, the rear AC blows ice cold and every other day the front starts blowing warm.

But if I turn the front blower all the way down for a minute or so and turn it back on it blows ice cold for a moment then warm again.

I've been doing some research and it seems like the problem might be a clogged orifice tube.

 

[fixmiester]

Thats very likely. This past summer I had to replace my AC dryer and my orifice tube filter, as well as blow out my condenser because I was having really weird freon pressures. Even though my rear evaporator was cooling okay, my front system was not cooling at all. Since the rear system uses an expansion valve, and the front uses an orifice tube, the back system was not clogged up yet. The orifice tube was pretty difficult to get to, but I was able to replace it. Works fine since then.