janitrol heater

jcthomas · #1 10-04-02, 08:52 PM

I am having a heater problem. My 1969 T337 heater will not ignite. You can hear the pump working, but no ignition. I haven't taken apart the fuel line to see if is giving any fuel.

It did work for a while when I brought the plane back across the US a few months ago. But now it doesn't work and here in the Northeast the white stuff will be here shortly.

I couldn't find much in the manuals except for the wiring diagram.

Any suggestions would be helpful.

John

Mark Hislop · #2 10-05-02, 08:38 AM

There are several safety switches in line ahead of the ignitor. You could have a bad high-temp switch, or a bad air flow switch which would prevent the ignitor from working. You could also have a bad ignitor. I think it's rare for lack of fuel to be the problem. Follow the schematics and it is fairly easy to check each of the components electrically to see if they are working or not.

Mark

GMAs · #3 10-05-02, 09:28 AM

their is a manual for the southwind heater that cessna put in the planes... and I think Skyking has one now... I have it on micofish.... and one day I will get a projector so that we can put it on the web from it...but, the expense is still too high right now... to go out and get one...

but,... back to your problem... I suggest that you contact Skyking and get a copy of his... as they are I believe almost non existant... G.M>

SkyKing · #4 10-05-02, 04:45 PM

I don't have the manual from Cessna yet, but it's "on order"... I'm also awaiting arrival of the Janitrol B2030 Series Heater Service and Overhaul Manual from Kelly Aerospace.

John... Do you know when the last pressure decay test was run on your Janitrol? There are two AD notes on the heater that affect the 42D36 combustion air pressure switch that's mounted on the upper forward part of the heater unit, as well as the combustion tube itself and the fuel regulator shut off valve. The applicable AD notes include 96-20-7 pertaining to the integrity of the combustion tube (a flame erosion problem) and the combustion air pressure switch, and 2002-08-01 pertaining to the JanAero Series 14D11-7.5 fuel regulator and shutoff valve.

The old style 42D36 combustion air pressure switch is generally the culprit and will keep the heater from operating and it is primarily through shops messing with the switch through over adjustment and consequent de-coupling of the pressure sensing spring that's inside the unit which will render the switch inoperative and your heater ka-put. What generally happens is, you will hear the fuel pump and regulator clicking away, the blower on full high, and the heater either trying to intermittantly light-off or not at all. After a light-off attempt and you shut things off, you should see some fuel dripping from the overflow drain tube which comes through the left lower front engine cowl.

Of course, you could have other problems, like the thermostat switch as the base of the pilot's rudder pedals, or if you don't have the levers in the right position and there isn't sufficient air flow through the heater, this too will cause the combustion air switch to stop the process and the heater will flame-out. Very seldom is the 39D18 spark plug a problem. The spark plug is $80 bucks.

You'll probably have to have the unit checked by a qualified mechanic that is FAMILIAR with the Janitrol B2030 series Heaters as installed on the 337's and who has a copy of the service and overhaul manual (P/N 24E25-1). The AD note on the combustion air switch and combustion tube has to be done every 24-months or 100 heater hours TIS (Time in Service), whichever occurs first. This will still be the case after you replace the older problem- causing 42D36 combustion air pressure switch with the newer 94E42 switch. They're about $160 bucks.

BTW, since the Janitrol heater gets its fuel supply from the left tank, make sure the overhead console fuel shutoff valve is in the green or yellow crossfeed position.

In the meantime, if you want to check the combustion air switch for proper continuity, with everything shut off, you can disconnect the two leads going to the top of the switch-- it's a round thing with a flat top and a black phenolic area on top with two screw terminals that sits on top of a short standpipe at the forward part of the heater, adjacent to the spark-plug and ahead of the main terminal block. After you take the two leads off, connect an ohmmeter or continuity tester across the switch terminals. If the unit is good, you should have an 'open' indication. If you get a 'closed' indication, i.e., a short between the terminals, then you have a bad combusiton air pressure switch.

Hope this helps.

SkyKing

GMAs · #5 10-05-02, 07:27 PM

wouldn't it be nice to have a liquid cooled engine.. and it would do away with all that gas heater stuff... smile... its nice to dream isn't it...

Glad to hear that you two are getting togeather... I have the microfish and I guess some day I should get a reader to computer thing going... but, I haven't found one yet... and the print out on the paper.. shilver is not that good... but, if you have any questions I will be glad to look at the book for you... on the screen of the micro... G.M> GMAs

Bob Cook · #6 10-05-02, 08:48 PM

Janitrol heaters are scarey things! Something I prefer to leave to the specialists.

There is a mandatory SB out on the fuel regulators for leaking. I had to replace mine. There is a replacement cumbustion chamber that will eliminate the 100 hr inspection..... but...... not inexpensive.

Bob

Tony Giantonio · #7 10-06-02, 11:43 AM

Hi JC, I wish I could find my book but alas its somewhere. You should have a pressure decay check accomplished within the last annual, if not its a good idea to get that done before winter. As for your trouble with out my book I won't render any solution except the name of a repair facility that I have used with great success. I've often called and they talked me through problems. Real nice people. Their name is Harold Haskins Inc. out of Dothan, AL. tel no. 334 983-3189 you can give them a call for some help. Sorry thats all I can do for you at this time. Hopefully the book will be published on here soon. Tony

jcthomas · #8 10-06-02, 09:40 PM

Hi!

I appreciate all of the good advice. I think Skyking has focused on my problem. I am going to give it the test and see if it is. I agree with Bob that the heater is a scarry thing when you think of the com bustion and all of the ads. I believe from looking at the log books my heater has met the first ad but not the second one. Need to get it done the right way to make sure I don't have a fire out of control.

I can't imagine enjoying my Skymaster without the help from all of you on this site. It is probably one of the reasons I chose to go with this plane as a choice for a twin.

John

Paul Sharp · #9 10-07-02, 07:19 PM

I recommend following the advice you got from skyking:

"You'll probably have to have the unit checked by a qualified mechanic that is FAMILIAR with the Janitrol B2030 series Heaters."

Get someone who knows the things and knows how to service them. THey're not hard to do if you're experienced. The trick is finding one who is. There are many who'll say they work on heaters all the time, etc. But getting one who knows what he's doing makes the diff. between spending $1500 and $500 real fast.