Usage:
All Caterpillar Machines With Pressurized Cabs
- SUPPLEMENT: 05/28/90
SERVICE MAGAZINE; MARCH 5, 1990; PAGE 13; "4C5623 Smoke Candles Can Help Locate Air Leaks In Cab," on all Caterpillar machines with pressurized cabs. Disregard the first sentence in Step 7. The correct first sentence for Step 7 follows:
7. The candle will emit smoke for about 30 seconds.
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New 4C5623 Smoke Candles (12 per box) are available. The smoke candles can be used as an aid in locating cab air leaks. An air leak in a pressurized cab causes the cab pressurizer to draw in excessive outside air, to replace the air that has leaked out. This can cause several problems:
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- 1. Outside air filters will plug prematurely, because they are filtering a larger amount of dirty air.
- 2. Plugged outside air filters will result in a loss of cab pressure, which can allow dust to enter through cracks and other openings.
- 3. Additional dust in the cab can cause the recirculation air filter to plug prematurely, resulting in reduced heating, cooling, and defrosting. The additional dust also tends to clog the fins on the air conditioner evaporator core.
- 4. The increased amount of outside air drawn in, adds to the heat and humidity load of the air conditioner. This could possibly result in a lack of cooling complaint.
- 1. Outside air filters will plug prematurely, because they are filtering a larger amount of dirty air.
Many cab air leaks are difficult to locate, because they may be in an inaccessible part of the cab.
To use the smoke candle correctly:
1. Place the machine in an outdoor location where there is little wind.
2. Be sure the cab windows are closed securely.
3. With the engine off, run the cab pressurizer fans on "HI" speed.
4. Place one smoke candle on a metal pan or plate, on the floor of the cab, away from the seat cushion or combustible material.
5. Light the wick of the candle, and leave the cab immediately.
6. Close the cab door tightly.
7. The candle will emit smoke for about 10 minutes. During this time, observe all points where a large amount of smoke is seen escaping. Be sure to observe underneath the cab and on all sides of the cab.
8. Open the cab door and wait until smoke is no longer visible in the cab.
9. Turn the cab pressurizer fan "OFF".
10. Remove the remains of the smoke candle.
11. Repair the point(s) of leakage noted in Step 7, by replacing missing or damaged seals or other parts, and caulking with RTV sealant if required.
NOTE: The smoke is very fine and will be slightly visible at nearly every seal and joint. It is not desirable to seal every insignificant leak, but only those where a larger quantity of smoke is seen.