I have an old nutone 656 bath fan and I need to reinstall it and it has 4 wires I need to know how to hook it up

Hi -- I just spent a couple of days taking out the old assembly, cleaning all the parts (layers of dust coats) and putting the 9093N back in order to fix the noisy fan. The cold air coming back in is from to the heating and I'd guess the heating element is busted. Yes, you can run it in both airflow modes: ceiling air exhaust and hot air blown to the floor. That said, the noise level on mine hasn't gone down. So I'll look for the replacement assembly. Good luck!

Excellent how-to for replacing the motor/fan assembly is found on these Google blogs:
http://nutone763rln.blogspot.com/
http://nutone8664rp.blogspot.com/

The replacement motor is available from several sources online. The best way is to purchase the new motor assembly. All you need to do is remove the blower housing from the ceiling, there are three screws that hold the motor assembly in place. The whole job takes about five minutes. Here are a few sites with the motor.
http://www.centralvacuumstores.com/Bath-Vent-Fan/NuTone/Motor-Assembly/0696B000-Motor-Assembly.php http://parts.broan-nutone.com/nutone/Shop?actn=quicksearch&searchtype=all&indextype=7&keyword=qt100l&Search.x=0&Search.y=0 http://www.cshincorporated.com/product_info.php/manufacturers_id/33/products_id/11272

you need to see if there is a block in the pipe going out of the bath, if open see if the wires are hooked up wright dont cross wires thi will cause a problem, you may need to upgrade your fan to bigger one if to small.good luck

Here is the link to a replacement lens:
http://www.centralvacuumstores.com/Bath-Vent-Fan/NuTone/Parts/84999000-Lens.php

The additional wires are for a starting capacitor, not included with the motor. The easiest way to hook-up is to order the Outlet Assembly p/n 88617000 (available at Coastal Tech Supply.) The assembly includes the capacitor, connector, and shroud; and will replace the existing outlet assembly in the housing. Minor electrical work is required to remove the old assembly and install the new one.

The replacement motor is available for that fan model. The NuTone part number is the 0696B00. It can be purchase from these sites:

http://parts.broan-nutone.com/nutone/Shop?actn=quicksearch&searchtype=all&indextype=7&keyword=qt100l&Search.x=0&Search.y=0

http://www.centralvacuumstores.com/Bath-Vent-Fan/NuTone/Motor-Assembly/0696B000-Motor-Assembly.php

http://www.ventingdirect.com/nutone-0696b000-power-unit-assy-packaged/p431404?y=16&term=0696b000&x=41

You'll be able to access the motor to service it and the wiring junction box from inside the bathroom. Please rate this answer if it was at all helpful.

It sounds like you need a new motor. They sell for about $40.00 and are pretty easy to change out.

Go to the link below and you can order replacement parts for the QT 100L
http://parts.broan-nutone.com/nutone/Shop?DSP=30115&PCR=1:21000&IID=QT100L