MACS Monthly Newsletter - 2022 - JUN4

The A/C cooling issue sounds like low refrigerant,
but as noted, the pressures are normal, and so the
technician starts looking at other possibilities. However,
it makes a lot more sense to start with what
originally seemed most likely, because if you can
absolutely eliminate something, you've made progress.
Even if low refrigerant charge turns out not to
be the cause, it could have been. So, we'll point out
once more something we've noted over the years:
pressures are NOT a good indicator of state of
charge. At best a very low charge will be indicated
by low pressures. But with today's precise charge
systems, it doesn't take much of a refrigerant loss
to affect performance. However, this model, with its
rear HVAC, has an OE charge of 39 oz, one of the
greater refrigerant charges in a vehicle today. With a
front-rear system in a big van, a loss of even 6-9 oz
( just 15% of the total) may be enough to create the
A/C cooling problem without a noticeable drop in
system pressures. Yes, a system with 30 oz remaining
can suffer a measurable drop in performance.
With an SAE-certified recovery/
recycle/recharge machine, technicians
should have learned that they
can recover the refrigerant pretty
quickly, and in this case the system
was just low enough on charge
(9 oz / 23%) to affect performance
and a recharge did restore normal
performance.
But there's more to the picture on
this particular make of vehicle.
Ford has found that this evaporarefrigerant
tor
core was prone to surface corrosion
(and
resulting
leakage) from a buildup of airborne
debris. And if you're thinking, " Uh
oh, " a technician is thinking, the
whole climate control system under-dash
has to be removed and
disassembled to replace the evaporator.
Here, at least there's a bit of
better news: Ford is now supplying the evaporator
only in an evaporator case assembly (containing a
new evaporator and factory-installed sealing). This
is an approach Ford has taken several times over the
years-you can re-use the blower case. If it didn't,
the evaporator case would have to be cleaned, as
the debris buildup is not confined to the core face.
However, Ford has an intake air filter kit available,
to keep out airborne debris (yes, it should have been
an OE installation, we know). But once it 's installed,
the filter should be replaced every 20,000 miles. See
Figure 4. If the customer is lucky, there's no leak, just
high-normal refrigerant loss from the front and rear
systems over the six years, or leakage from a couple
of accessible underhood joints. In that case, you
may be able to just clean a debris-laden core and
case with an aftermarket system, such as AirSept,
and install an aftermarket inlet air filter at the cowl
air inlet. Otherwise, to R&R that evaporator case is
factory flat-rated at 6.5 hours, which like many factory
times, sounds optimistic. v
Figure 4: In addition to complete evaporator case replacement, Ford repair
procedure includes installing a cabin air filter, which becomes a replacement
part.
June 2022
4
MACS Service Reports
alldata.com
http://www.alldata.com
MACS Monthly Newsletter - 2022

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