3515CH HVAC
- Thread starter denjen
- Start date
- Views: 2163
Thought would update for others that might have this issue
Symptom - No cold AC, compressor clutch does not engage
Troubleshooting
1) Test compressor clutch engages (unplug compressor and jump from battery)
2) Use gauges to check refrigerant pressure
Engine and AC off (static - is refrigerant in system, pressure dependent on temp and humidity)
Engine running and AC on, check numbers per service manual)
Needed to unplug compressor and jump from battery
Numbers were close to service manual recommendations (ran 5 - 10 mins)
At this point appeared to be electrical in nature....
3) Check pressure switch on condenser (used continuity tester), next checked for pressure switch voltage, tested good (need ignition switch on).
NOTE: per the schematic it shows a 'dual pressure (high/low) switch'
NOTE: Page 756 of 15 series service manual
Since blower, AC button appeared to work decided to verify the anti-freezing sensor (left side, 2 wire plug, part of evaporator in roof), checked out good
4) Engine running, blower motor set to 2, AC on, checked for power on compressor relay plug (labelled E1 and is blue/white wire), no power. Removed and tested per service manual (used example page 775) and found continuity bad.
5) Replaced compressor relay and AC blowing cold air....
(So far.... LOL)
Symptom - No cold AC, compressor clutch does not engage
Troubleshooting
1) Test compressor clutch engages (unplug compressor and jump from battery)
2) Use gauges to check refrigerant pressure
Engine and AC off (static - is refrigerant in system, pressure dependent on temp and humidity)
Engine running and AC on, check numbers per service manual)
Needed to unplug compressor and jump from battery
Numbers were close to service manual recommendations (ran 5 - 10 mins)
At this point appeared to be electrical in nature....
3) Check pressure switch on condenser (used continuity tester), next checked for pressure switch voltage, tested good (need ignition switch on).
NOTE: per the schematic it shows a 'dual pressure (high/low) switch'
NOTE: Page 756 of 15 series service manual
Since blower, AC button appeared to work decided to verify the anti-freezing sensor (left side, 2 wire plug, part of evaporator in roof), checked out good
4) Engine running, blower motor set to 2, AC on, checked for power on compressor relay plug (labelled E1 and is blue/white wire), no power. Removed and tested per service manual (used example page 775) and found continuity bad.
5) Replaced compressor relay and AC blowing cold air....
(So far.... LOL)1. Depending on outside temperature and air flow those pressures could be good to a little high.
2. The condenser and receiver drier are combined to one unit for the 20 series.
A vertical tube on the condenser looks much larger than usual. Probably the same for the 15 series. And the manual still doesn't show the difference in serial number break.
3. A lot of companies us a pump and a preset quantity of refrigerant on systems. It's faster than the old method of getting it right with gauges, and as long as you have the right numbers it works. If you have the wrong numbers due to the wrong serial number break it won't work.
Edit the switch with a probe in the core is for temperature control, the low pressure switch is on the line between the core and the compressor.
I have a 20 series not a 15, I've not had to fix it yet but I work on semi trucks
2. The condenser and receiver drier are combined to one unit for the 20 series.
A vertical tube on the condenser looks much larger than usual. Probably the same for the 15 series. And the manual still doesn't show the difference in serial number break.
3. A lot of companies us a pump and a preset quantity of refrigerant on systems. It's faster than the old method of getting it right with gauges, and as long as you have the right numbers it works. If you have the wrong numbers due to the wrong serial number break it won't work.
Edit the switch with a probe in the core is for temperature control, the low pressure switch is on the line between the core and the compressor.
I have a 20 series not a 15, I've not had to fix it yet but I work on semi trucks
Last edited:
Yes, condenser and receiver are combined on 15 as well. I cut/pasted from the schematic about the pressure switch.
I traced the lines from the evaporator all way to the compressor and couldn't find a switch in the line, so if somebody that has a 15 series knows where it is please add it here.
I traced the lines from the evaporator all way to the compressor and couldn't find a switch in the line, so if somebody that has a 15 series knows where it is please add it here.