[lbpesq]

My heater goes on and off by itself with the temp control turned all the way off (counter-clockwise). The <acronym title='heater control valve'>HCV</acronym> is relatively new and appears to be working fine. Suggestions?

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[flash]

the HCV is controlled by vacuum, and defaults to "on" when there is a vacuum leak

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[lbpesq]

Can vacuum leaks be intermittent? Sometimes the heater will stay off for a while (at least 1/2 hour), at other times it will come on for 2-5 minutes, then go off for 2-5 minutes, etc.

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[flash]

that's exactly what mine did. not sure why. found a cracked vacuum hose, fixed it, and problem gone

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