Transcript A/C Design Verification Tests

A/C Design Verification Tests
• A/C Performance:
– Conducted at 43 C (110F)
– Vehicle is soaked till average interior
temperature reaches 140 F and then tested at
30 min @ 30mph, 30min @ 60mph, 10min
idle in drive and 20 min idle in Neutral.
– Maximum head pressure requirement is 400
Psig at end of 30min idle
A/C Critical Parameters
• Compressor Endurance Test (New test starting
06-07 model year)
– Vehicle is tested at max speed and WOT, wide open
throttle, at 100 F and 110F for 20 min followed by
10min idle in drive and 20 min idle in neutral
– Maximum head pressure requirement is 320 psig
during high speed and WOT and 400 psig at end of
idle
– Maximum compressor discharge temperature is
265 F
Future Improvements
• Ford Climate Control is phasing out scroll
compressors on all Ford North American
applications, replacing orifice tube with TXV for
refrigerant control, and implementing high
capacity condensers on all vehicle applications.
• By 2009 All vehicles will have piston pump
compressors ranging from 150cc on small
vehicles to 213cc on large vehicles.
• For 2007 programs, Econoline diesel will still
have 115cc scroll compressor. Econoline gas will
have 180cc piston compressor and New HD FSeries will have 213cc piston pump
Future Improvements
• The new piston pump compressors meet new
Ford engineering specs.
• The new compressors are more robust for high
speed, high head pressure, slugging and clutch
cycling.
• By 2009, all vehicles will have high capacity
condensers.
• 2007 1/2 HD F-Series and Econoline gas
engines will have high capacity condensers.
Econoline diesel will still have the regular
capacity condenser.
Future Improvements
• By 2009 most of our vehicles will have TXVs
replacing Orifice Tubes as refrigerant control
devices to improve idle performance. Few
applications such as HD trucks and Econoline
will keep the orifice tube for the moment.
• Replacing orifice tubes with TXVs will require a
different way of determining the proper amount
of refrigerant charge when adding an aux unit for
rear seating comfort.
A/C Critical Parameters To Watch
• When adding aux units or making changes to OEM
designed system the following critical parameters should
be monitored
– Compressor head pressure should not go beyond 430 psig when
idling for longer than 30 minutes at ambient above 95F
– Compressor refrigerant discharge temperature (skin A/C line
temperature) should not go higher that 265 F under extreme
conditions (High speed/high ambient or long idle, more than 30
minutes at ambient above 95F)
– Compressor refrigerant inlet temperature (Skin temp.) should not
be colder than the evaporator out. This is an indication of
compressor flooding.
– Do not use copper brass heater cores or joints in the aux units.
A/C Critical Parameters To Watch
•
Determining the proper amount of refrigerant charge and oil after adding aux units
requires controlled environmental chambers. When this facility is not available, the
following process should be followed
– For system with Orifice tube in front and TXV in the Aux
• Run the system, both front and Aux in high blower speeds, open
windows and air recirculation mode. Engine speed 1500 rpm, 90F
or higher ambient (best if is 110F) Use and industrial fan to blow air
in front of the condenser to simulate ram air to the front end. (This
test can also be run at 40mph vehicle speed)
• Add refrigerant until the front evaporator inlet and outlet tubes skin
temperature cross over. (Cross over is evap out temp cooler than
evan in temp as refrigerant is added)
• Turn the aux system off and repeat the step above.
• Add 2 ozs of charge as charge protection.
• Monitor head pressure and discharge air temperature throughout
this process. A slight increase in discharge air and head pressure
are expected after adding the charge protection.
• As a rule of thumb adding an aux unit will require an additional 4 to
5 ozs of oil to the OEM front system label amount.
•
Compressor discharge temperature should never go above 265F during the charge
determination process.
A/C Critical Parameters To Watch
• TXV Selection for Aux System.
– It is very important to select the proper TXV size when
adding aux units.
• Oversize TXV will cause hunting that is evident in suction
pressure rising and falling during normal operation. It also
flood the compressor with liquid refrigerant that causes it to
fail prematurely.
• Undersize TXV will cause poor performance and higher
superheated gas to compressor that causes the compressor
discharge temperature to reach its critical temperature of
265 F.
• Recommended super heat setting is 10F
• NOTE: NEVER USE ORIFICE TUBES FOR
FRONT AND AUX SYSTEMS.
A/C Critical Parameters To Watch
Summary
• Under all driving and weather
conditions, the compressor
discharge temperature should be
under 265 F and compressor
head pressure should be under
435 psig after idling for 30
minutes at ambient up to 110 F.
A/C Lines & Fittings
• The following information is critical to ensure the sealing and
performance integrity of A/C lines and joints.
– No thread sealer or Teflon tape on threads
– Sealers do not work on orings and cause more problems
– Hand crimping gives unequal forces on hoses leading to gross leaks
or high leak rates
– Adjust the screw fitting on the bottom of the TXV to change super
heat setting (if super heat changes are required for TXV function)
– Avoid dissimilar metals from touching
• Aluminum and steel touching create corrosion problems
• Use non conductive rubber to isolate the dissimilar metals
• Most sensitive on tubing, less on steel nuts touching blocks
– Design or select components such that they don’t create oil traps in
the lines “U” shape line routing
A/C Lines & Fittings
• The following is a good practice to ensure
proper function of A/C lines and joints
– Protect underbody lines from stones with convolute or
foam insulation
– Route convolute or foam so that the slit is on the
bottom of the assembly to avoid corrosion (Water
accumulation)
– Route lines away from heat sources (Exhaust pipes),
heat will damage orings, hoses and crimps
– Insulating suction line will improve performance
– Use lines going to the rear that are equal to or less
than ½ inch (Liq. Lines. For better performance)
– Use lines coming from the rear that are equal to or
larger than 5/8” (Suc. Lines. For better oil in
circulation)
A/C Lines & Fittings
• Good practice Cont’d.
– If possible remove shutoff or adapter valves that
come with the front system
– Recommended hose is Goodyear 4860 & 4890 or
equivalent hoses with similar specs for liquid line
– Recommended hose for suction line is Goodyear
4880 & 4869 or equivalent hoses with similar specs
– Use only HNBR orings for connections
– Keep orings and seals free of contaminations. Even
very small hairs, dirt, lint and other debris will create
leaks
– Many joints are torque sensitive. Follow torque specs
for all joints.
Recommended Single Fittings
Dual Slimline Fitting, it contains a
oring and compression fitting
Recommended Dual Fittings
Single Slimline connections
for Expansion Valves
Part Numbers and Components
• Currently there are many types of fittings that
come on a Ford Vehicle. They include dual
slimline, single slimline, face compression oring
peanut, tube O, quick connects, single radial
oring peanuts, and manifold blocks.
• Orings & seals are specific to its fitting type
• For any questions, contact your Body Builders
Advisory Service Representative