| Author | Message | ||
| John & Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 307 Registered: 9-2007 Posted From: 24.183.21.246  Rating: N/A |
Well, I am going back over today to do some electrical testing (Not my strong suite). I have accessed the underfloor motors and both appear to be in good condition. Today I will start doing some circuit tests to see if I have power to them. The question I have is in my service manual at one point it alludes to the bus motor running before starting the heater/airconditioner motors. Is there some switch in the heater fans system that requires this, or was it just that in the case of the air conditioner (disabled now) that the pump needed to be turning before the fans were tested? The bus is inside a building and running it inside is not really a viable option. Thanks in advance for any input, John T | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 315 Registered: 3-2006 Posted From: 216.198.139.38 Rating: N/A |
John In my setup the engine has to be running before the large heater motors will run. They draw so much juice that it will kill the batteries if the generator isn't charging at the same time as they are running. The gen relay has to pull in to alow the motors to run. You could use a jumper wire from the batteries to the terminal on each motor to see if they run okay. Use a large size wire like battery jumper cables and there will be a large flash when you touch the terminal on the motor. Make the connection fast and hold it steady. Do not make the connection at the battery flash as the battery could explode with the normal amount of gas that it generates just sitting. Bill | ||
| Len Silva (Lsilva)
Registered Member Username: Lsilva Post Number: 328 Registered: 12-2000 Posted From: 72.187.35.208  Rating: N/A |
You will have to check your schematics but, yes, I believe that there is a relay operated from the "R" terminal of your alternator that controls power to the motor relay. These fan motors draw a large current and would quickly kill the batteries without the engine running. If you can find it, you can defeat the circuit and run the fans for testing. | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 700 Registered: 3-2007 Posted From: 71.53.153.91  Rating: N/A |
On somr of the gmc they use an air pressure switch so that when the pressure builds,the grn will start to charge and a little mor pressure the fans will operate. Some have seperate controls for each. Gomer | ||
| John & Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 308 Registered: 9-2007 Posted From: 24.183.21.246 Rating: N/A |
Well thanks for all the info. I found that there are two solenoinds between the two motors. One goes direct from power to the motors, one goes through a series of what I assume are coils for slowing down the motor speeds. I have power to the "high speed" soloniod but it doesnt operate. I can jump across it and the motors will run. But when i try to jump from the hot side of that switch to the motor side of the "slow speed" switch, the motors do not operate and I get a spark, like something is grounded. Sorry for not describing it better, but as an electrician, I make a great truck driver! My thoughts are that the coils that make them run at lower speeds are somehow not functioning and that has caused the breaker that feeds that "slow speed" solonoid to stay open. Does this make any sense to anyone? This is like trying to teach advanced calculus to a orangutan! |