1954bubba1954 Report post Posted February 11, 2021 dash air & heat will blow only cool air; will not he at or cold; replaced thermostat still no reading on gauge or heat or cold Share this post Link to post Share on other sites
kaypsmith Report post Posted February 11, 2021 (edited) Welcome to the forum. How long has it been blowing cold air? A little info about your RV will be helpful in getting better answers. Is it class A, B, or C? Is it gas or diesel? what brand is it? Has it ever since you owned it been able to heat? Edited February 11, 2021 by kaypsmith Share this post Link to post Share on other sites
dickandlois Report post Posted February 11, 2021 Bubba, Welcome to the FMCA Forum ! Yes ! as Kay mentioned we need more information. When the thermostat was changed was the cooling system flushed ? If you are talking about a pickup truck or a Class series chassis need Model, Make and year of the chassis and is it powered by by gas or Diesel engine. Rich. Share this post Link to post Share on other sites
1954bubba1954 Report post Posted February 11, 2021 it has worked till recently. it is a 2007 fleetwood southwind 37c; gas; class a; Share this post Link to post Share on other sites
kaypsmith Report post Posted February 11, 2021 (edited) Thanks for the response. Being a gas class A, means that it has a motor at the front which helps rule out the long run of hoses from the rear which would be expected from a diesel pusher. So we can now expect that the hoses are shorter and less likely to be kinked and restricting the flow of coolant to the heater core. There should be two hoses going to the hearer core, feel of those hoses and expect at least one of those to be pretty warm once your temperature gauge is at operating range. If this test is good, then the next step is to check the door that allows heat from the heater core to enter the evaporator chamber and then pushed by fan into the cabin. The door is usually operated by a vacuum valve on a gas model the vintage of your coach, some are operated by an electric solenoid. If the door is not opened up you could be blowing cold air. Most vehicles of your coachs age have temp gauge, what does that gauge show? Edited February 12, 2021 by kaypsmith Share this post Link to post Share on other sites
wildebill308 Report post Posted February 12, 2021 1 hour ago, kaypsmith said: There should be two hoses going to the hearer core, feel of those hoses and expect at least one of those to be pretty once your temperature gauge is at operating range. If this test is good, then the next step is to check the door that allows heat from the heater core to enter the evaporator chamber and then pushed by fan into the cabin. Kay, I think there may be a valve used to control the hot water flow into the core. I have seen them not working before to. 1954bubba1954, Does your engine reach operating temperature? What temp thermostat did you install? Do you have the Ford chassis? Bill Share this post Link to post Share on other sites
rayin Report post Posted February 12, 2021 (edited) When the engine is at operating temperature feel the heater hose from the engine to the heater core, is it hot to the touch? If not, feel closer to the engine on the engine side of the flow control valve, again is it hot to the touch? If yes, that valve is faulty or the control is not opening the valve. On older vehicles I have seen people remove that non-working valve and replace it with a 1/4 turn ball-valve; then simply open the valve for heater use, close for air-conditioner use.. Edited February 12, 2021 by rayin Share this post Link to post Share on other sites
dickandlois Report post Posted February 12, 2021 This is one style of heater control used on the V-10 engines. The Heater control valve should look like the valve that looks like the one on the left side of the picture. The hose going into the front should be hot with the engine warmed up. If there is vacuum supplied to the small vacuum line at the top of the valve. then the line running away from the should also be hot. This is the hose that feeds the heater core. Check vacuum system is working, before replacing the valve. Rich. Share this post Link to post Share on other sites
jleamont Report post Posted February 12, 2021 6 hours ago, dickandlois said: This is one style of heater control used on the V-10 engines. YUP, and they are notorious for sticking and leaking. Share this post Link to post Share on other sites
1954bubba1954 Report post Posted February 21, 2021 On 2/11/2021 at 5:38 PM, kaypsmith said: Thanks for the response. Being a gas class A, means that it has a motor at the front which helps rule out the long run of hoses from the rear which would be expected from a diesel pusher. So we can now expect that the hoses are shorter and less likely to be kinked and restricting the flow of coolant to the heater core. There should be two hoses going to the hearer core, feel of those hoses and expect at least one of those to be pretty warm once your temperature gauge is at operating range. If this test is good, then the next step is to check the door that allows heat from the heater core to enter the evaporator chamber and then pushed by fan into the cabin. The door is usually operated by a vacuum valve on a gas model the vintage of your coach, some are operated by an electric solenoid. If the door is not opened up you could be blowing cold air. Most vehicles of your coachs age have temp gauge, what does that gauge show? temp gauge does not move Share this post Link to post Share on other sites
wildebill308 Report post Posted February 21, 2021 (edited) On 2/11/2021 at 12:57 PM, 1954bubba1954 said: replaced thermostat still no reading on gauge or heat or cold 1 hour ago, 1954bubba1954 said: temp gauge does not move I can't help you without more information. These cryptic statements are useless. Make shure the wire to the temperature sending unit is installed properly. What temp thermostat did you install? Use a infrared thermometer to see what temp the engine is running at. It will get warm even with no thermostat. Use a infrared thermometer to see what temp the heater hoses are after running it long enough to warm it up. After 30 min of fast idle is the top radiator hose warm/hot? is the thermostat housing hot /warm? Is the system full of coolant? I am still thinking it is the heater control valve. Bill Edited February 21, 2021 by wildebill308 Share this post Link to post Share on other sites
kaypsmith Report post Posted February 21, 2021 (edited) If you removed the thermostat, the coolant system probably needs burping. If the outside temperature is pretty cold where you are located, you will need to make sure that there is no voids in the coolant system. That system depends on pressure to keep the fluid moving as well as the water pump. As mentioned before, use an infrared thermometer to see if the radiator is getting warm/hot, and check the temperature of the motor itself. If engine is not heating, you may have real problems. All as Bill has already pointed out. Edited February 21, 2021 by kaypsmith Share this post Link to post Share on other sites
dickandlois Report post Posted February 21, 2021 (edited) Bubba, The picture I posted is one of the style vacuum controls used on the Ford V-10 engines and a number of members know this! Have you checked to make sure there is a vacuum on the control line to this control ???? No vacuum and you will not get any heat from the engine. If you do not understand this information , It might be best to visit a Ford repair center. Is the engine getting hot or warming up? Rich. Edited February 21, 2021 by dickandlois Share this post Link to post Share on other sites
