B190 Enthusiasts

Hi guys, I have a 1993 - B190 48000 miles with generator. During my last two monthly generator runs I've found the generator running but the roof top A/C heat strip has stopped operating. When i switch to the Microwave, it doesn't work either. However. If the generator is shut off for a few minutes, there is a click somewhere after the generator starts and the heat strip ( and microwave) works again for a while. No fuses are blown in the converter / inverter (?).
Shore power works as it should for AC heat strip and micro. Any suggestions where to check?
Gary

Interesting. I know the generator has to be running for a minute or so before the output is strong enough to run appliances (that's the click you're hearing). Sounds like the inverter may be going but I'd like to hear from the electrical experts out there.


Cliff

Gary,

I can give you a couple of things to check. This should help to at least narrow the problem down a little. I also own a 93 B190 that I did extensive 12v work on last spring. I'm imbedding a piece of a circuit diagram I built of the modifications I performed work only on the 12v side, but I'm pretty sure the diagram accurately reflects the 120v side as well for our B190s
The first thing I would do is check to see if the AC outlets were working while running the generator. If they aren't I'd check to see if breakers were thrown. I don't think this has anything to do with your problem but I believe the AC outlets are on a separate circuit breaker and would at least confirm that all AC power was off while the generator was running.

Since you indicated that the microwave and heat strip worked when run from shore power, I suspect the issue is with your transfer switch. The automatic transfer switch controls which source, shore or generator, power is used in the vehicle. Sometimes the switch contacts will respond slowly and stick in the open position especially if the switch is 20+ years old as it was in my B190. Last summer I Had a problem with the transfer switch recognizing that I was plugged into shore power and would sometimes take 5+ minutes to connect to the circuit breakers and power the AC side of the van. I corrected this by having the switch replaced and all is working fine. My bet is this is your problem. The clicking you here is the transfer switch doing its job. But just because its clicking it doesn't mean it working.

The one thing I assume is that you are unplugging the shore power before firing up the generator. I've never tried running the generator while connected to shore power so I can't provide information about what happens in this situation. The transfer switch might get confused since both power sources are on simultaneously. I suppose the generator might not be putting out sufficient power to kick on the transfer switch. Either way you will need to get a look at the transfer switch under the couch to verify the power output from the generator.

If it is the transfer switch I believe the cost for the switch and install labor was about $200.

Good luck! Hope this helps.

Mike

If you have an AC voltmeter you can check to see that you are getting 120 volts out of the generator(or whatever it is supposed to be). I did this by taking an old cord with a plug on it and connecting the bare wires to the meter while the generator was running. Possibly if it is not in the correct range it is cutting out to protect the 120v appliances. With this method you can set the gen rpm to get the needed voltage. I think the gen spec is for a certain rpm, but a special meter is needed to measure this, which I did not have.

Thanks Mike. I'll give this a try. Is it possible to clean the transfer switch contacts or are they sealed?
Gary

You might be able to clean the contacts but I'd just go ahead and change it out to avoid future problems. You'll have to look at them when you get access to it. Mine were pretty bad and since I'm gone the entire summer I didn't want to have to deal with it on the road. The cost of the switch itsel was about $75 if I remember correctly.

Mike