Lochinvar 999 - 750, 399 TROUBLESHOOTING GUIDE 990,000 - 2,070,000 Btu/hr Models, Step

Installation and

Service Manual

TROUBLESHOOTING GUIDE

990,000 - 2,070,000 Btu/hr Models

	Does the power
Step 1	switch provide
	power to the
	control panel?
	YES
Step 2
	Combustion air
	blowers come on.
	YES
Step 3
	Status light(s) does
	not blink 1 flash
	continuous.

				Check the switch and/or
				the line voltage.
	NO
								Exchange ignition
							Check all safety limit	module.
		Is there 24VAC at B2 on				NO
							devices and voltage from
		the terminal strip.
							the transformer to B2.
NO								Check fan relay
							NO
								board. Is there
			YES				Does F2 on ignition module	120VAC on red
						YES	have 120VAC?	wires, pins #7 &
							YES	#9?
		Check 24VAC at TH					Check flow switch, all connectors
		(orange wire) on ignition
					NO		behind control panel and Tekmar
		module(s).						YES	NO
							output pins #16 and/or #20.
							Is there continuity from the fan		Replace fan
							relay board to fan(s)?
NO				Check air pressure					relay board.
				switch 24VAC on tan
				wire (N.O.)				YES

YES

NO

YES

Replace fan.

Replace air pressure switch.

Step 4

Does igniter(s) proof?

YES

	24VAC at PS (tan wire) at ignition module
	and/or connector plug for proving relay secure.
	Check Amp draw for 3.1 amps or
NO	greater.
	YES
	NO

Check air pressure	YES
switch for correct
pressures.	NO
Is Air Switch
bouncing?	YES

Correct air settings may have to clean burners/heat exchanger.

Replace igniter if less than 2.75 amps.

		Do the gas valve(s)	NO
		open and getting
		24VAC?
Step 5
Is the flame sense	NO	YES
signal to the ignition
module 5uA dc or		Check inlet/manifold gas pressure
greater?
		both static and dynamic. Check
		down draft.
YES
Step 6
Unit is running.
	NO
		Call our Technical
		Service Department
		1-800-722-2101

Is 24VAC present at the main unit connector
(3x5 amp plug) red and/or red - black wire,
block position #01 and #02?
YES		NO
Replace gas valve.
	Check voltage at fan relay
	board. No Voltage at pins #10
	(red) and/or #02 (red-orange)
	check ignition module pin #05
	(replace RLY2402 if no
	voltage).	No Voltage at pins
	#08 (red-black) and/or #03
	(red-white) check Tekmar
	controller pins #17-18 (red-
	black) and/or #21-22 (red-
	white) input/output voltage.

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