LMTV - M1078 Alarm going Off (Dual-tone)

So - started this am - I belive it is the dual-tone alarm. Manual says associated with the Troop Transport Alarm / Van Door Alarm .. I dont have one either of those.

It starts of faint, then gradually get louder until it sounds like the low-air alarm.

Any thought? point me in another direction?

NO issues of problems noted with brakes / air pressure / lights /transmission. I have NO warning light lit on the dash display and no error codes from the Transmission.

The only thing I do notice is that the temp gauge never moves and I don't get hot air from the vents.. (coolant levels are good)

Thanks!

sounds like a bad alarm mine works when it wants to.

just tape it over?? grin
I was out , in the snow this am going over everything I could and/or found in the TMs I have to resolve.
The dual-tone alarm ONLY goes off for the Troop Switch or Van Door - right?

I think the 2 tone alarm is the driver alert. Even without the switch the harness going to it is still usually there. Maybe its pinched somewhere and shorted. There is a valve that opens coolant flow to the heater with one of the levers on the heater. Could just be something as simple as the cable going to the valve came off.

There are 3 leads on the sonalert horn/buzzer in the panel. One is +12V power in, one goes to the brake switches and gives you a steady tone when the circuit is completed. and the other goes to the troop/door switch and gives you the pulsed tone when that circuit is completed. If you are not using it you could disconnect it from the sonalert and insulate it. troop sw should be wire number 32 going to TL178 on the buzzer.

You should be getting some kind of warm air out of the heater if the heat knob is pulled out. If not, as Superman suggested, the cable to the valve may be a problem, or a line for the heater may be kinked/pinched or something may be plugged.

As for the temp gauge, well these things pump coolant thru the heater if the valve is open, Thru the expansion tank, thru metal pipes across the front of the engine to the air compressor, and also down thru the transmission cooler(thru a restrictor). The transmission pumps a bunch of oil thru that cooler so you have heat being distributed to a bunch of surface area before the thermostat ever thinks of opening to send coolant to the radiator. If it is cold out, you are not going to see much gauge action untill you put enough load on the engine to overcome all this parasitic cooling capacity.