Pressure Checks 2000 Excursion

[hbabler]

I will test the engine fan and if it checks okay do a full load test like y’all describe and post the results back here.

I have only had it about 6 months. It had a leaky manifold hose assembly and a dirty evaporator so when I changed those I elected to change the compressor and dryer as well as I figured that it couldn’t hurt anything.

[bohica2xo]

Fan clutches wear out. And the 9 blade plastic fan is a big load on that clutch.

I would use a Motorcraft YB3157 Clutch.

I would also inspect the plastic fan blade carefully. I had one come apart after a new clutch was installed.

Motorcraft YA225 is the fan blade.

Aftermarket clutches only last a year on the F450's around here.

[hbabler]

Here’s an update.
The fan clutch seems to be doing okay. It won’t move more than an inch or two when cold. I can hear it engage when the truck gets hot.

Pressure for today.
96 degree ambient. (Not sunny though so the heat load wasn’t as bad as normal)
1900 rpm for 2 minutes, doors open front and rear on high recirculate.
High 285
Low 45
Vent 55

When I misted the condenser the pressures dropped quickly. (I may have applied too much water)

Do I need a condenser? I noticed I am getting a little heat bleed through when the AC off so I purchased a new heater shut off valve and I will swap that tomorrow.

Any other ideas as to what I can try next? Am I expecting too much out of this AC? Our 2008 suburban has a much colder AC both at idle and driving.

Also here are the idle pressures just in case.
Idle pressures:
High 215
Low 51
Vent 60

[Cusser]

Here’s an update.
The fan clutch seems to be doing okay. It won’t move more than an inch or two when cold. I can hear it engage when the truck gets hot.

Test that fan clutch when its HOT. If it spins too freely, replace it. Because you stated that misting condenser caused the pressures to quickly drop.

[hbabler]

So I checked it this morning after driving to work and it’s not as tight as it is when it’s cold.

I can spin it about one blade in either direction. Do I need to replace it? It appears that everything is pointing that way.

Thanks

[bohica2xo]

285 psi @ 96f ambient says you are not getting good condenser performance. That test is a good analog for leaving work at 4pm after the truck sits in the sun all day. You will have the cabin fan on max with the throttle open - and low ground speed.

The fan clutch or the condenser (or both) need help. How does it cool on the road at 45 to 55 mph & 1900 rpm?

The water on the condenser shows you where the pressures can be.

I would inspect & clean the air path through the heat exchanger stack. Bugs & dirt can block airflow through the whole path, reducing airflow. Use a strong surfactant like Simple Green or Purple Power sprayed full strength in to the fins & allowed to soak for a few minutes on a cold vehicle. Flush with a garden hose nozzle - a power washer or other high pressure water source can bend fins, so stick with the hose.

A good fan clutch will wake the neighbors on a cold start. It will spool down in a few minutes. At 96f ambient, idling for 4 or 5 minutes at a light should lock it up - and make it howl leaving the light. We still have some 7.3's in service here in tow trucks and shuttle vans - I can hear one coming down the street anytime the ambient is over 90f. F450's just won't die.

[hbabler]

Okay that makes sense. I am certain the fan clutch is weak. I’ll order one and clean the stack and try again.

It cools pretty well at 40-45 MPH. Somewhere in the upper 40’s.

Thanks for all the help!