RV Repair: frunace, car exhaust, x file

Question
QUESTION: we replaced the circuits board turned on the thermostat and the  rv filled up with terrible smell and no heat came out just cold air  we are living in the rv at present and need heat any suggestions as to what the problem could be

ANSWER: Hi Dee. I am not sure what boards are in the Tsats. Are you sure it was the thermostat you had worked on? It could be anything. Can you tell me more? What did it smell like? What kind of coach. make model and year? Let me know.

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QUESTION: we replaced the circuit board on the furnace  it is a mallard pull type it is 87   the smell is like a car exhaust

Answer
Hi Dee, I have answered a ton of furnace questions. Read back on how to troubleshoot the Limit and sail switch. What has me puzzled is that you say there is a smell of exhaust but the furnace blows cold? X file! You may be smelling LP.(propane) and this can happen when the tank is empty. The other possibility is a bad electrode. The wire to it, or the electrode itself is bad. If LP is full and you can hear the ignitor trying to light the flame. Then the electrode is most likely bad. Good Luck