Carver P4 low output

[dougalthedog999]

Hi,

 

I have a Carver P4 fitted to my camper (1999 La Strada Avanti).

 

It turns on and heats up but very soon the fan slows down and the heat output is reduced.

 

The heater has been mounted on it's side so that the intake is above the outlet - I am wondering if this is causing the intake thermistor to be heated by the hot air from the bottom outlet leading the heater to reduce output.

 

Any other suggestions would be welcome!

 

Thanks.

 

 

[Keithl]

Try making a very simple baffle to hold between the inlet and outlet and see if that helps. A piece of hardboard, aluminium or even cardboard may suffice as a trial.

 

Keith.

[dougalthedog999]

Hi,

 

I have tried sealing the vents and putting an insulating mat between them but I suspect the heat may be transferring internally.

 

Does anyone have a service manual / wiring diagram for the P4?

 

Thanks.

[paulmold]

I have manual but can't see how to attach 7 pages. Perhaps send me a PM with your email address.

[Derek Uzzell]

Intimate details of the Carver P4 air-heater can be found on these links

 

http://eat-drink-men-women.blogspot.com/2015/04/carver-p4-furnace-for-isolde-part-1.html

 

http://eat-drink-men-women.blogspot.com/2015/04/carver-p4-furnace-for-isolde-part-2.html

 

http://eat-drink-men-women.blogspot.com/2016/03/carver-p4-furnace-for-isolde-part-3.html

 

http://eat-drink-men-women.blogspot.com/2016/03/carver-p4-furnace-for-isolde-part-4.html

 

http://eat-drink-men-women.blogspot.com/2016/03/carver-p4-furnace-for-isolde-part-5.html

 

A Carver P4 would normally be installed ‘flat’ as shown in the attached photo. Air is sucked from within the leisure-vehicle’s interior via the heater’s air-intake (green arrow) heated inside the appliance and forced from the heater’s air-outlet (red arrow). Flexible hoses are normally attached to the air-inlet and air-outlet and, In such cases, the end-fittings of the two hoses may be close together and postioned side-by-side (as in the photo) or one-above-the other.

 

I’m not sure if Carver forbade mounting a P4 on its side (Perhaps Paul could check in his P4 manual?). But as the air-inlet and outlets could be mounted in close proximity and in any orientation, I doubt if ’side-mounting’ that puts the cool-air intake directly above the hot-air outlet will be provoking this issue.

 

Given the age of this heater, if it were straightforward it would be worth removing the heater’s outer cover to check the state of the interior. Carver was subsumed by Truma around Year 2000 and I well remember seeing a P4 heater bench-running at Truma(UK)’s premises about then. I asked what had been wrong with it (the P4 had something of a patchy reliability reputation, particularly regarding their printed-circuit board) and was told that nothing a good interior clean hadn’t cured. Apparently the heater had been installed in a horse-box and, when opened up, was found to be full of dust and bits of straw.

 

This company still advertises Carver P4 repairs

 

https://www.arelectronics.co.uk/contents/en-uk/d29_Carver-P4-Blown-Air-Heater-Repairs.html

[paulmold]

The P4 i had in my 97 Symphony was mounted on its side so that obviously didn't cause a problem . Mine stopped working but managed to find one on eBay and swopped it over, cheaper than having it refurbished by that company mentioned above and I sold the duff one on eBay for spares.

 

I don't actually have the manual or I would happily send it on but I copied it for the Auto-sleeper forum.

[Derek Uzzell]

These links relate to the ebay entries for Carver P4 heater repairs by A&R Electronic Developments Ltd

 

https://www.ebay.co.uk/c/25008583236

 

https://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=153291421566&category=108845&pm=1&ds=0&t=1609838032000&ver=0

 

There is an online copy of a Carver P4 trouble-shooting table

 

https://motorhomer.com/threads/carver-p4-heater-not-working-help.37883/

 

but this deals with the heater failing to operate at all, or starting up and then developing an issue that causes a flashing-light fault-code to display. However, (as I understand Terrys’s postings) his Carver P4 starts and runs without displaying a fault-code - just won’t maintain the heat-output it should.

 

The attached files (taken from a 1999 Swift handbook) advise on how to operate a P4 heater. As Terry implied, the heater’s output is controlled by an internal sensor that measures the temperature of the air that is being sucked from the habitation area into the heater.

 

If Terry has owned his 1999 La Strada for a while and the P4 heater has been working ’normally’ until now, it may be safely assumed that the heater’s ‘mounted-on-its-side’ installation is not the cullprit. So - unless there’s a simple explanation like the heater needing a good clean inside - a repair is likely to be needed.

 

(I’d contact A&R Electronic Developments Ltd for advice...)

[_Chris]

I used A&R Electronics to repair the Carver P4 in our van. The problem was that there was no heat which was caused by a faulty board.

 

The company repaired it for a fixed cost but also gave the unit an overhaul and test which I suspect was long overdue on a 20 year old unit.

[dougalthedog999]

Hi,

 

Thanks for all the info above and sorry for the late reply.

 

I have the original installation user manual but was hoping someone may have a service manual / wiring diagram.

 

I guess the next step would be to remove and clean out (it dates back to 1999) as Derek suggests, whilst doing so I will see if I can test if the thermistors are working correctly.

 

I'll report back once I have had a chance to do this!

 

Thanks again.