thought I had found a thread about my problem, but mine is a bit different. Instead of the air and the radio going "dead", they go into a coma, sort of.
I just bought this '99 RR 4.0 SE last weekend. Yesterday whilst driving around and listening to the radio with the air conditioner working magnificently, I felt the need to change the music. I pressed the appropriate button but nothing changed. I tried another button, and nothing. I tried manually going up the radio dial... then changing the volume..... and ultimately trying to turn the radio off, and then on again. All without any change at all. The radio kept playing the station I had originally been listening to, and at the same volume. The air conditioner was fine, no problem there. Later in that same trip I tried changing the volume again........ and surprise ! it now worked. I now can change the volume, the station, change from listening to the radio to listening to CDs, etc.
Now today when it got to 85 degrees and I wanted the air conditioner on, I turned it on and it worked fine.... for about a half hour, then I noticed that the fan was blowing at low speed, and the air coming forth was not real cool. I attempted to change the temp, and the blower speed.... no change. I did notice that a little warning icon had lit up on the face of the unit. The manual indicates that the system has self checked and found a problem. Later in my trip today, after having been in a store and coming back to the car, I start the engine and the air conditioner starts working as it should; cold air and lots of it. The warning icon is still lit however. And the radio is doing fine so far.

So what does all this mean? how can the radio still work, but not be able to be controlled?

Having been the owner of a Land Rover for only 6 days, I am so perplexed

 

Its a land rover, thats whats wrong with it LOL! You will see random stuff like this occur off and on for no apparent reason. Just as randomly as it started, the problem will disappear (mine likes to do this with the blinker). The radio is probably just getting old, and electronics do tend to bind up after awhile and just need a reset. As for the air conditioning. What settings do you have it on, "auto"? If I want the A/C at max, I set the temps to lo, turn the direction of the air to the front vents, and then turn recirculate on. Next time it doesn't work as well, try doing that and see if it improves.

I'll bet what is happening, is a blend motor is getting stuck causing the air to not blow in any specific direction, which will cause the check book light to come on as well as ineffective circulation. Before you turn the fans to max. let the blend motors do their thing so they do not have as much resistance to fight when moving, next time you start the rover.

 

thanks for the suggestion about the air conditioner. I'll give it a go next time.

As far as the radio. I have already considered putting in a new one; not an original equipment radio. . . .something that can handle an MP3 player input; but I so hate modifying such a nice vehicle from its original state.

 

you know....... I thought you had given me the spot-on answer for my air conditioner problem. I made a trip to the super tonight and tried your suggestion. Turned the air on manual, had the blowers set to low, and the thing operated splendidly. The warning icon even went out. Cold air, and plenty of it. Wonderful. Then on the way home, following the same procedure. . . it was working okay until I was sitting at a traffic light. While waiting for the light to turn green there was a very noticeable drop in the blower level, the air coming out wasn't quite as cold as it had been just a few moments earlier, and the warning icon came back on.

Guess I'll have to keep searching for the cause of this problem.

thanks for your suggestion though.

 

Check the cooling system, sometimes if there is a problem it will cause the A/C to work weirdly at times.

 

Mine has not done this to me, but there is a possibility the door (if you had it on recirculate) decided to disengage to prevent too much carbon dioxide to build up in the cabin. And well, it got stuck and the light came on lol. Its a very weird system, full of all sorts of little surprises. In some cases it is very intelligently designed, in other instances (like making the gears plastic in the blend motors instead of metal.) the design is just plain stupid. For the radio, I'm not sure if your model has a cassette player. If it does, there are little devices that mimic a cassette and then you just plug your mp3 player into it. OR the other approach, you can buy a device that connects to the mp3 and then broadcasts a small am signal that your radio can pick up on.