Sounds like we all had the same problem with this type of heater. I have tried blowing through the all the air lines including the one that goes to the motor and nothing is working. What is going on? It only works of a few sec.??? Help...

Resources for Whirlpool/Craftmaster gas water heater:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html

Problem might be diminished air supply or bad venting. Clean the air intake located on bottom of water heater using compressed air or feather duster. Air intake screen is series of openings as wide as razor blade and can easily clog.
Clean the combustion parts and burner. Bleed air/water out of gas line. Check gas pressure.
Check for pilot and venting issues on link above, including tight house, and other gas appliances and vent fans pulling draft down the water heater vent pipe, etc.
Also see service manuals for each type of gas control valve, and replacement steps for each type.

To troubleshoot this types of problem,click the link below :----http://howtobyme.blogspot.in/2012/02/heater-blows-only-from-defrost.html
--------Go through the procedure to confirm the issue.------
Engine Overheats and heater blowing cold? http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html
---------Heat blows cold on drivers side and hot on passenger side? http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html
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This will help.Thanks.

Try cleaning the pilot out sounds like flame is too small and when main burne rlights it takes gas away from pilot .

Clean pilot try blowing it out with can of air or with air line carefully .

turn the gas on real slow. The air in the line is blowing out the pilot

If you have a new heater core inside, some of the probable causes of your lack of hot air include the two heater hoses, heater control cable, water pump, and damper/vacuum door. A handy diagnostic article that explains this will is the following:
http://yourhandymanzone.com/Your_Handyman_Zone_How_To_Pages_Vehicle_Car_Zone_Cars_Trucks_Vans_Heating_System_Heater_Blowing_Little_No_Hot_Air.htm

Hope this helps!
Brad

the fuel line goes to the back of nozzle and the air line goes to the front.the air line and fuel line are not clear on that unit.sounds like some one changed them.also the fuel filter goes in the unit backwards from what the arrow shows.check your air pressure.you need to put a gauge on it so it is correct.

This sounds like an air damper is not operating, maybe a cable sticking or a vacuum line come off.

Sounds like you have a common problem with infrared heaters. They are very dust sensitive and they will light and then go out when they are dusty. If you have already tried to blow it out at home you need to take the heater to your propane dealer who will take the heater apart and blow it out correctly. They will then hook it up to their gas line and make sure that the problem is fixed. I hope that you haven't blown up into the bottom of the heater where the gas line is connected. There is a diaphragm up in there and if you blow into it you risk messing it up to where it won't work at all.

Specifications for air blow guns include pressure capacity and air line connection type. Pressure capacity or maximum rated pressure is rated at the air inlet and measured in pounds per square inch (psi). Many types of air line connectors are available. Quick-release connectors contain fittings that are attached internally. By contrast, push-on connectors include barbed ferrules. Air blow guns use several types of national pipe thread (NPT) connectors, most of which are inch-based and female. Important NPT measurements include threads per inch (TPI) and outside diameter (OD). 1/8” NPT connectors have 27 TPI and an OD of 0.405”. 1/4” NPT connectors have 18 TPI and an OD of 0.540”. 3/8” NPT connectors also have 18 TPI, but an OD of 0.675”. 1/2” connectors have 14 TPI and an OD of 0.840”. #10-32 NPT threads are also available. Air line connections that can swivel or pivot are suitable for applications that require versatile positioning.

Hi Watertec00,

I am not familiar with this heater but it sounds like it could be a blockage in the main gas line into the heater or perhaps a blockage to the pilot gas line and maybe starving for gas. Best bet first is to check the main gas line from the heater. Easiest way to do this is to remove it from the heater and blow it through with compressed air. Then try the heater again. If that doesn't fix the problem then you can try blowing compressed air down through the pilot line. Could be a little dirt creating a blockage there. Then try the heater again. If it still does the same thing then try removing the panels to expose the heater's piping. If you can remove the main pipe into the heater from the gas and blow compressed air through it it should clear any obstruction from both the main line and the pilot. If this doesn't work then I would think you have a more severe problem and will need to take it to your local Heater Repairer. Hope this helps.

Regards
Bryan