Chapter 3 HVAC Tools, Equipment, and Service Information 47
tighten the compressor drive belt, a belt tension gauge,
Figure 3-15, is needed. To use the belt tension gauge, use
the handle to push the center lever away from the two
side levers. Slide the tool between the belt and release the
handle. Then read the tension on the gauge.
Another type of belt tension gauge is shown in
Figure 3-16. This type of tension gauge measures belt tight-
ness by measuring the belt defl ection under a certain pres-
sure. To use this kind of tension gauge, turn the gauge sleeve
until the end of the sleeve is at the proper belt tightness
marked on the barrel. Then push the metal bar downward
until it lines up with the line on the lower end of the barrel.
Next place the gauge on a fl at section of belt and push
downward until the metal sleeve reaches zero. If the metal
bar is pushed above the gauge line, the belt is loose.
Vacuum Pumps/Gauges
The hand-held vacuum pump and vacuum gauge,
Figure 3-17, is used to apply and measure the effect of
vacuum on HVAC system diaphragms and control valves.
The pump assembly develops vacuum, which is measured
on the gauge. To use the gauge, remove the hose to the
vacuum operated device. Then operate the pump to apply
vacuum to the device. Observe the gauge. If vacuum cannot
be developed, or bleeds away rapidly, the unit is leaking.
Also check for operation of the related linkage as vacuum is
developed. If the linkage does not move when the vacuum
is increased, the linkage or the door is stuck.
HVAC System Service Tools
Once the problem has been located, the HVAC system
must be repaired. Many repairs can be made with ordi-
nary hand tools. Many service jobs require wrenches with
large jaw openings. These large size wrenches are used to
loosen the large fi ttings used on many refrigerant lines. A
few HVAC service jobs require special tools.
Compressor Service Tools
Most shops prefer to replace entire compressors rather
than repair them. If a compressor is being repaired, the fol-
lowing tools may be needed to service the seals and internal
parts. Servicing older compressors may require additional
special tools. The technician should consult the proper
service information for information about these tools.
Figure 3-15. This belt tension gauge provides a direct reading
of belt tension. (Ford)
Belt tension
gauge
Figure 3-16. The belt tension gauge shown here is set to the
proper reading and then the belt is defl ected.
Figure 3-17. The small manual vacuum pump and gauge is
used to produce a vacuum for checking vacuum operated
accessories such as air door vacuum diaphragms and vacuum
heater shutoff valves. It can also be used to check the operation
of vacuum switches.