III-71
C. Drive Belt – The drive belt should be tight and in good condition. Use a belt ten-
sion gauge to check tension (120 pounds maximum). With experience, you can feel
belt tension by twisting the belt. Try feeling belt tension after using the gauge, when
you know the tension is correct. Replace belts if they are frayed or look worn.
If the clutch pulley/belt alignment is obviously off, you need to loosen the com-
pressor or mounting bracket, or both—and use the alignment bar to line up the clutch
pulley with the drive pulley. Tighten compressor mounting bolts first, then the bolts
holding the bracket. The mounting bracket should have slots or other means of
adjustment to allow you to adjust the tension of the drive belt. When you use a pry
bar to apply tension, be sure you do not pry against the compressor. Pry against the
mounting bracket.
3. Check Hoses and Fittings
Check all hoses and fittings. Look for places where hoses flex when the cab is tilted.
Any places the hoses or fittings are fastened, clamped, connected, bent or secured are
potential wear points. This also applies to places where hoses are not clamped or sup-
ported but should be (often near the condenser). All of these spots are potential leak or
damage points. Tighten, re-fasten, add, or replace as indicated by your inspection.
4. Check for Refrigerant Leaks
System refrigerant leaks can be anywhere but there are obvious places. You can spot
some by looking for signs of refrigerant oil forced out with refrigerant leakage. One
location leaks frequently occur is the compressor shaft seal. The shaft and seal are
hidden behind the clutch assembly, but centrifugal force will throw the oil off the
shaft and against the engine, bracket or whatever is close. Check these points when
you examine the compressor clutch and mounting bracket. A solution of soap and
water applied around potential leak points works well for detecting leaks. A leak in the
evaporator may be indicated if you feel around the condensate drain hole and find oil
present.
Note: You can add inexpensive dry nitrogen gas to the system instead of
R-12 if system pressures are low. Dispense the gas at no more than
200-250 PSI as this is sufficient pressure to cause or indicate a leak
point in the AC system. AC service procedures for complete system
recovering of refrigerant, evacuating, and recharging are covered and
illustrated in
C
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a
p
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e
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9
.
Note: A leaking heater core could also result in coolant at the condensate
drain.
Inspection & Maintenance
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