| The original factory vacuum operated heater control valves are no longer available for the 74-78 z's with factory AC. The cars with no AC or aftermarket AC didn't use this valve, only one of the mechanical valves. See listings. We rebuild these valves ourselves and they do have certain criteria that has to be met. If we happen to be out of stock, it usually only takes us a few days to get more done depending on our work schedule. We do not sell the rebuild parts outright. Note: the picture shows a new valve not a rebuilt unit. The rebuilt units will be painted black. We use a new valve pic from our archives because it shows up better. For your trade in valve to be useable towards a core charge refund it must be unmolested, complete, in rebuildable condition, and the vacuum portion of the valve itself must still be fully functional. In other words it must still hold a vacuum and still have adequate movement when activated to be acceptable. If the vacuum valve portion doesn't work, then we have to rebuild your valve. You cannot use it as a trade in, we would have to rebuild yours only. To avoid the core charge then send us your valve first with your contact information. We'll contact you once the valve is ready to ship. If your existing valve leaks coolant due to worn out seals, that is not a problem, it will usually still be acceptable as a trade in. There are 2 parts to that valve and the coolant leak is on the lower section whereas the vacuum portion is on the upper section. To order one of these valves you need to first check out your valve and see if the vacuum portion is still functioning. If your heater still works but the valve just leaks then that tells us that the vacuum portion of your valve is still intact and acceptable as a trade in. The core charge is 75.00 for this valve and it is not included in the posted price. The core charge will be added to the price of the valve automatically by the store when you place your order. When we receive your unmolested rebuildable core we'll refund your core charge at that time. If you send us a core that has a breech in the diaphram, we will only give you partial credit for your core return which will be at our disgression. If your core has excessive corossion then it may not be acceptable for a trade in. If you have any doubts about your core return, contact us directly and talk it over with us. Temporarily to make the valve leak less or in some cases not at all, make sure that the coolant level is about 2 inches below the radiator neck and leave your radiator cap on loose so it will not build up pressure. In most cases this will either slow the leak down or stop it entirely. Be careful doing this if the air temp is over 95 degrees F. One thing you should NEVER, NEVER do is use stop leak of any kind in these cars cooling and heating systems. That will only cause more problems with your car. We usually carry all the under dash and under hood cooling system hoses in stock for most models of z's from 70-83. See listings. Last update 12/11 | 
