I have an 84 Vanagon = Westy. It's new to me, and really nice. I want to spend lot's of time in it, but It has = no air conditioning, and I feel a little silly sitting in it and sweating for = no good reason. How much should I expect to pay for an after-market installation = of AC? Can it even be done? Is it bad to let the engine idle with AC = running for any length of time?