Electrical Resistance Checks; Setup; Heater Sensor Probe; Thermostat - Graco B Series Instructions-Parts List Manual

Troubleshooting –
WARNING
Always disconnect the main electrical power to the
heater before removing the front control panel
covers (216, 217) to reduce the risk of serious
bodily injury from electric shock.

Setup

1. Measuring the resistance of a part helps determine
if it is working properly. Determine the approximate
temperature of the part; if the heater was operated
recently, the temperature will be high. If you get a
measurement other than those given in the
following procedures, replace the faulty part.
2. Shut off the main power to the heater and remove
the appropriate control panels.
3. To remove wires, use the accessory tool, P/N
110–968 or a 3/16 in. wide screwdriver. Insert the
tool into the slot below each wire on the terminal
block, push the tool away from the wire and pull
out the wire. See Fig. 9.
4. To reconnect the wires, push the tool into the slot,
slide in the wire and release the tool.
Tool 110–968
Fig.
9

Heater Sensor Probe

1. Remove the heater control panel (216).
2. Unplug the connector P1 at position J2 on the
heater circuit board in question. See Fig. 10.
3. Check the resistance across the two outside termi-
nals of connector P2. The resistance should be:
45K to 55K ohms at 77 F (26 C), or
10K to 20K ohms at 120 F (49 C)
4. To replace the sensor probe (256), see page 22.

Electrical Resistance Checks

Thermostat

1. To check continuity from inside the wiring junction
box, remove the wires from connector T1 and
check continuity across the wires.
2. To check continuity at the thermostat, remove the
front heater element shroud (238). Check for conti-
nuity across the terminals at each switch, with one
lead disconnected and after pushing the reset
button. See Fig. 14, page 22.
3. If there is no continuity achieved, replace the ther-
mostat. See page 22.
Optional ATC
(Ambient Temperature Compensator)
1. Remove the heater control panel (216).
2. Unplug the connector P1 at position J1 on both
heater circuit boards and the hose circuit board.
See Fig. 10 and 11.
3. Check resistance across the two terminals of each
connector P1. The resistance should be:
45K to 55K ohms at 77 F (26 C), or
10K to 20K ohms at 120 F (49 C)
4. To replace the ATC, see page 30.

Heater Element

Use this chart to identify the heater assembly and
heater element wires used in your Foam-Cat Heater.
Foam-Cat Flow
Heater Capacity
Model No.
235–260 30 lb/min
235–840 (13.5 kg/min)
235–259 15 lb/min
235–839 (6.75 kg/min)
1. Remove the heater control panel (216).
2. Using the procedure in Setup, disconnect the
wires indicated below.
3. Check the resistance across wires 7 & 8, and 9 &
10, on the RES board. Check the resistance
across wires 17 & 18, and 19 & 20 on the ISO
board. The resistance should be as follows. If an
open conditions exists, check the hi-limit thermo-
stat. See Fig. 10.
20 to 25 ohms at 77 F (26 C)
4. To replace the heater element, see page 24.
(normally closed)
Heater Heater
Assy. No. Element Wire
Numbers
235–840 7,8,9,10 RES
17,18,91,20
ISO
235–839 7,8 RES
17,18 ISO