could this be the issue in my 94 with no heat? air blows just fine, but no heat at all. its a 94 reg. cab xlt with the 3.0 V6 5 speed standard with no AC at all. all ik is that getting to work at 7am here in upstate NY is really really cold and getting home from college around 9pm is the same and the lack of a working defroster is pretty unsafe in the rain that we get here. how can i test this?

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1994 Ranger XLT
3.0 V6
5 Speed manual
135k...so far
Full size bed
Regular cab
Pioneer CD/Tuner deck