rossvtaylor
Adventurer
If it helps, my tiny vacuum pump for those heater valves is in the cabinet above the pass-through window. I know each one's different, though, and you (Oz) have a full walk through... So probably no help.
Freightliner ambulance conversion project.
- Thread starter Ozrockrat
- Start date
rlrenz
Explorer
A Medic Master mounts the heater/AC evaporator directly over the walk through - or where the walk through would be. Here are some photos that may help you:
Photo showing a Hoseline 'stat (the white control that says Hoseline)
Photo showing a current Hoseline CM-3000 thermostat
AC wiring - note light blue color
Photo showing a Hoseline 'stat (the white control that says Hoseline)
Photo showing a current Hoseline CM-3000 thermostat
AC wiring - note light blue color
Ozrockrat
Expedition Leader
Ok chased back and found a loose wire in the wiring mess under the console in the cab. Still never found the thermostat. Mine has a switch for heat/AC in the module. There is 2 sets of wires in the blower area. I am figuring one of these must be the thermostat but there is definitely nothing in the module within the users reach.
Now thinking along the lines of running both while we go down the road. I think actually running a duct into the cab may be a good idea. Have it directed to the 3rd seat area.
Oh and the rear AC unit is way way better than the cab one.
Now thinking along the lines of running both while we go down the road. I think actually running a duct into the cab may be a good idea. Have it directed to the 3rd seat area.
Oh and the rear AC unit is way way better than the cab one.
rlrenz
Explorer
A set of wires in the blower area kind of makes sense. Normally, a standard Hoseline thermostat is installed on the wall of the module so it can be adjusted easily - it senses with an internal bimetal strip. The newer CM-3000 digital thermostat has a separate sensor on a cable. The sensor is placed in the return air duct, usually close to the AC evaporator so it will respond quickly to changes, like a door being opened.
I wonder if your original thermostat wasn't installed close to the evaporator for better (and faster) temperature control? It would still be easily adjustable once an EMT knew to open the evaporator door, and it may have been put behind a door to minimize non-EMT personnel fiddling with it.
KKK-A-1822 (the gospel for our era of ambulances) requires that manufacturer-installed wiring be labeled along it's length with what it does, and a wire number. In the case of my Medic Master, #2 is for the module AC, and #5 is for the module heat.
You could check to see if any of the mystery wires are hot when the heat/AC switch is turned on - there might also be some labeling on the other wires.
If you have a 3-speed blower, you should have 3 wires coming from the blower switch to the resistor bank that's mounted on the face of the evaporator. There were some 4 speed blowers, but they are fairly rare. By the way - the blowers are a failure item, so if you ever run into a good used blower, you might want to stash it for the future.
You might be able to use a conventional home thermostat to control your HVAC system, but I doubt that a home thermostat has much of a current rating. Select Tech has the standard Hoseline thermostats available for $63, and it should hold up a lot better.
Have fun-
I wonder if your original thermostat wasn't installed close to the evaporator for better (and faster) temperature control? It would still be easily adjustable once an EMT knew to open the evaporator door, and it may have been put behind a door to minimize non-EMT personnel fiddling with it.
KKK-A-1822 (the gospel for our era of ambulances) requires that manufacturer-installed wiring be labeled along it's length with what it does, and a wire number. In the case of my Medic Master, #2 is for the module AC, and #5 is for the module heat.
You could check to see if any of the mystery wires are hot when the heat/AC switch is turned on - there might also be some labeling on the other wires.
If you have a 3-speed blower, you should have 3 wires coming from the blower switch to the resistor bank that's mounted on the face of the evaporator. There were some 4 speed blowers, but they are fairly rare. By the way - the blowers are a failure item, so if you ever run into a good used blower, you might want to stash it for the future.
You might be able to use a conventional home thermostat to control your HVAC system, but I doubt that a home thermostat has much of a current rating. Select Tech has the standard Hoseline thermostats available for $63, and it should hold up a lot better.
Have fun-
Ozrockrat
Expedition Leader
Thanks Bob. It does have the wires and resistor block. Then there is another set of wires going into the evaporator. These have been extended with non coded wires so I will need to chase back into the circuit to see where they go. For the moment I have it running and will wait until I can run a full diagnostics on the system. It had a little bit of pressure in it but not much (enough I felt I didn't need to get the circuit evacuated). But Tuesday I will take it to a local place, get them to recover all the gas out of both AC's, change the schrader valves and do a full leak test.
With our heat profile in Phoenix I am OK with not knowing where the thermostat is and just controlling it manually if it actually ever got to be too cold. And I have never checked to see if any of the heater circuit works
With our heat profile in Phoenix I am OK with not knowing where the thermostat is and just controlling it manually if it actually ever got to be too cold. And I have never checked to see if any of the heater circuit works
patoz
Expedition Leader
Bevan, you said it came from south Florida, right? With our heat and humidity, we don't use thermostats...we just have a toggle switch marked OFF/WFO! Seriously, the A/C in my house has been set on 72°, and has not been changed in over a year!
True story - Back in the mid 70's we stole..err I mean re-appropriated, a huge central unit from a building that was being torn down, and installed it in the bunk room of the main fire station where I worked. We just sat the evaporator unit at one end of the room, and poked the lines through the wall to the condenser unit just outside. It had no duct work, just a huge 90° elbow sitting on top of the unit, and no thermostat...just a toggle switch. It would be so cold in there in the mornings, you could hang meat, but it made for great sleeping between calls!
Seriously, the A/C in my house has been set on 72°, and has not been changed in over a year!True story - Back in the mid 70's we stole..err I mean re-appropriated, a huge central unit from a building that was being torn down, and installed it in the bunk room of the main fire station where I worked. We just sat the evaporator unit at one end of the room, and poked the lines through the wall to the condenser unit just outside. It had no duct work, just a huge 90° elbow sitting on top of the unit, and no thermostat...just a toggle switch. It would be so cold in there in the mornings, you could hang meat, but it made for great sleeping between calls!
Ozrockrat
Expedition Leader
Bevan, you said it came from south Florida, right? With our heat and humidity, we don't use thermostats...we just have a toggle switch marked OFF/WFO!
I think you hit the nail on the head. It does have a AC-off-Heat switch in the back on the switch panel. It also has a 3 speed blower rotary switch. Which is marked lo-Med-Hi (it should actually be marked "you cannot feel it, maybe a little bit, the strength of a dead seagull farting") actually the rear has 8 outlets and blows at 5mph. The front on high (which roars like an F35 taking off) is 5mph. Now compared to the wife's Toyota which has a 5 speed blower. low = 5mph and high is 18.5.
Even though I know it is probably a forlorn hope I will pull the blower (test it and see if there is a possibility of upgrading) and also pull the top off the evap and try to back flush it. There is just not enough airflow for the size of the evap and the capacity of the cab especially with the big windows. Also there is the problem of no insulation in the roof apart from the flimsy head liner and a fair chunk of steel in front with a lot of explosions happening that produces a little bit of heat.
So my thoughts on how to Phoenix proof the cab.
1- Insulate the roof, floor, doors and firewall (noise and heat)
2- Clear tint the side windows and investigate doing the windscreen as well.
3- One of those 1960 windscreen shades. (this one is a firm maybe)
4- Roof rack to provide the same effect as the safari tops on the old land rovers. (shade and airgap)
5- Check airflow through evap.
6- Check blower and see if anything can be done to increase airflow without increasing the noise too much.
7- 12v fan at the back of the cab area to move some air around.
8- Duct from the rear AC directed to the jump seat area.
9- Pray for cool weather.
10- Head for the hills. :sombrero:
Other alternatives:
a- Probably the easiest way would be to leave the puny cab HVAC for a demister and put something like a Red Dot system like they use on earth moving machinery on the roof.
b- Another alternative is a twin head split unit with one in the cab and one in the module running off either shore power when parked or an inverter while running down the road.
c- Trade it in for a Toyota.
scooter421
Adventurer
Lol....at least you've got some options! We've got similar problems with our rig. I am certainly insulating the cab. What materials or product are you considering for number 1 on the list?
Scooter...
Scooter...
Ozrockrat
Expedition Leader
scooter421
Adventurer
Okay cool, I don't know how I missed this good bit of info. Thank you.....again.
Scooter...
Scooter...
Ozrockrat
Expedition Leader
Yeah I thought it was very steep for a couple of switches but if I can get cruise control for under $120 I will call it a win (and it reduces Ross's bragging rights by a smidgen
)All I have to do is work out which of the 4 spare plugs goes to the Set Resume switch. Not as clearly marked as the module wiring.