Eldorado Intermittent A/C

[sh1178]

The A/C has worked fine since the compressor was replaced in 2005. Also, the A/C system was serviced a few weeks ago. Two weeks ago, it blew only hot air (while the outside Phoenix temp was 118). I took it in to the dealer; they kept it for two days and couldn’t replicate the problem – it worked fine for them. So they gave it back to me having done nothing to it. Since then, it works only intermittently. Whatever happens when I turn the car on is what keeps happening – that is, if it immediately blows cold air, it keeps blowing cold air until I turn the car off – or – if it immediately blows hot air, it does that until I turn the car off. It’s still over 110 most days here in Phoenix, so I’d really appreciate any insight. Thank you!