Quincy Compressor QPHT 20, Operator'S Manual

July 2004

11

TROUBLESHOOTING

Table 1 — Troubleshooting Guide

Symptoms

Cause

Remedy

A. Moisture downstream.

1. Refrigeration compressor not 

running.

2. Suction pressure reads above 

blue/green zone.

3. Moisture separator auto drain 

malfunction.

a. Check electric power supply.
b. If red light is on, call for factory 

service.

a. Clean the air cooled condenser 

(see Page 8).

b. Adjust hot gas bypass valve (see 

Page 9).

c. Check for defective fan motor and 

replace.

a. Check the auto drain operation 

(see Page 8).

b. Check for clogged drain line from 

auto drain outlet to floor drain.

c. Check the electronic timer for 

loose wires or evidence of burn 
out.

B. Oil downstream.

1. Oil filter malfunction.

2. Filter element dirty.

a. Check the drain operation.
b. Clean the drain if stuck or 

clogged.

c. Check the drain manual valve for 

clogging.

a. Replace element (see Page 8).

C. Low air pressure downstream.

1. Suction pressure below blue/

green zone. This causes freeze-up 
in the air systems.

a. Adjust hot gas bypass valve (see 

Page 9).

b. Low on refrigerant. Call for 

service.

c. To confirm freeze-up, shut off the 

unit for 15 minutes. Air pressure 
should come back to line pressure.

D. Continuous air flow through the 

moisture drain line.

1. Foreign materials lodged on the 

valve seat.

2. Short-circuited timer board.
3. Short-circuited PUSH-TO-TEST 

switch.

4. Defective solenoid valve.

a. Press the PUSH-TO-TEST switch 

several times.

b. Disconnect the drain lines to the 

solenoid valve and blow 
compressed air from outlet while 
pressing the PUSH-TO-TEST 
switch.

a. Replace.
a. Replace.

a. Replace.