This is normal
It is normal for ice drops to form which then melt when your machine defrosts. A light dusting of ice on the rear wall indicates your machine is working ok.

Ice will accumulate at the rear of the appliance
Always disconnect your appliance from the mains before you start examining it!
This solution applies to the following models:
- HBC 3050AK - 34900187
- HBC3150K - 34900096
- HBCA 230 FF - 34900040
- HBCA325K - 34900026
- HBO3780 A - 34900093
- HBRU 164AK - 34900025
- HBRU160/1AK - 34900182
- HBRU164/1AK - 34900176
- HCF5176A - 34000920
- HCF5176W - 34000919
- HCF5190A - 34001104
- HCF5190B - 34001105
- HCF5190W - 34001106
- HCF6185A - 34000926
- HCF6185TA - 34001189
- HCF6185TB - 34001186
- HCF6185TW - 34001187
- HCF6185W - 34000921
- HCF6185X - 34000925
- HCF6200A - 34000922
- HCF6200W - 34000928
- HCN7185TA - 34000923
- HCS5176A - 34000918
- HCS5176W - 34000917
- HCS6185W - 34000927
- HFFB 3050AK - 34900186
- HLS6163A - 34000915
- HLS6163TA - 34000916
- HLS6163W - 34000914
- HSBS 540A - 34900022
- HSXS 5085 - 34001113
- HTN7185A - 34000924
- HWC2335X - 34000888
- HWC2536DL - 34000889
- VCN6185A - 34000956
- VCN6185B - 34000957
- VCN6185W - 34000959
- VCN6185X - 34000958
- VCN7185A - 34001180
- HBCP 3050K - 34900254
- HBOP 3780 - 34900143
- HBRUP 160K - 34900258
- HBRUP 164K - 34900257
- HFFBP 3050K - 34900255
- HFLE 5485WE - 34001625
- HFLE 6085WE - 34001633
- HFOE 5485WE - 34001403
- HNC 5143WE - 34001627
- HNC 5174AE - 34001629
- HNC 5174WE - 34001628
- HNC 6185AE - 34001623
- HNC 6185WE - 34001620
- HNC 6200AE - 34001622
- HNC 6200WE - 34001621
- HRFA 54S - 34001632
- HRFA 54W - 34001631
- HST 5143WE - 34001626
- HSC185WE - 34001836
- HBCP 3050K (1) - 34900256
- HDCF 6182 W - 34002132
- HDCF 6182 X - 34002133
- HDFF 618W - 34002131
- HF18XK WIFI - 34002114
- HFF 618 DW - 34002134
- HFF 618 DX - 34002135
- HMN7182B UK - 34002108
- HMN7182IXUK - 34002107
- HMN7182W UK - 34002109
- HBCP3050/1K - 34900369
- HBCP3150/1KD - 34900368
- HFFBP3050/1K - 34900370
- HFLE54B - 34002031
- HFLE54W - 34002030
- HFOE5485WE - 34001624
- HFOE54B - 34002029
- HFOE54W - 34002028
- HL54WE - 34001786
- HSC17155BE - 34001797
- HSC17155SE - 34001796
- HSC17155WE - 34001795
- HSC574B - 34002027
- HSC574S - 34002026
- HSC574W - 34002025
- HVBF5172AHK - 34001954
- HVBF5172AK - 34001951
- HVBF5172BHK - 34002045
- HVBF5172WHK - 34001953
- HVBF5172WK - 34001950
- HVBF5182AK - 34002040
- HVBF5182AWK - 34002041
- HVBF5182BK - 34002077
- HVBF5182BWK - 34002106
- HVBF5182WK - 34002056
- HVBF5182WWK - 34002042
- HVBF6182BFHK - 34002038
- HVBF6182WFHK - 34001957
- HVBF6182XFHK - 34002039
- HVBS5162BK - 34002037
- HVBS5162SK - 34002036
- HVBS5162WK - 34002035
- HVTL542BHK - 34002044
- HVTL542WHK - 34002043
- HFF195BK - 34002251
- HFF195BWK - 34002254
- HFF195WK - 34002249
- HFF195WWK - 34002252
- HFF195XK - 34002250
- HFF195XWK - 34002253
- HSC185WE/1 - 34002193
- HSC536W - 34002167
- HVBF5192BHK - 34002206
- HVBF5192WHK - 34002204
- HVBF6182WFHK/1 - 34002195
- HVBF6182XFHK/1 - 34002196
- HVBFP6182W - 34002248
- HVBN6182BHK - 34002240
- HVBN6182BWDK - 34002242
- HVBN6182WHK - 34002237
- HVBN6182WWDK - 34002238
- HVBN6182XHK - 34002239
- HVBN6182XWDK - 34002241
- HBBS 50 UK - 34900459
- HBBF 50 UK - 34900460
- HVLN6172WH - 34002296
- HVLN6172XH - 34002297
- HCF5172BK - 34002381
- HCF5172WK - 34002320
- HCF5172XK - 34002319
- HCS5172BK - 34002348
- HCS5172WK - 34002321
- HCS5172XK - 34002322
- HTL552B - 34002307
- HTL552W - 34002303
- HCN6182WK - 34002317
- HCN6182BK - 34002318
- HCN6202BK - 34002350
- HCN6202WK - 34002349
- HCN6202XK - 34002351
- HSC 185WEHK - 34002383
- HBBS 100 UK - 34900454
- HBOP 3780/1 - 34900372
- HMN7182BK/1 - 34002373
- HMN7182IXK/1 - 34002374
- BHBF 172 NUK - 34900556
- BHBF 182 NUK - 34900557
- HBOL 172UK - 34900558
- BHBF 50 NK - 34900526
- BHBS 50 NK - 34900525
- HVBF195WK - 34002599
- HVBF195XK - 34002600
- HKTLS 604WHk - 34002604
- HTLP 130WK - 34002591
- HCSB 5172WK - 34002598
- HMNB 6182B5K - 34002569
- HMNB 6182W5K - 34002568
- HMNB 6182W5WDK - 34002570
- HMNB 6182X5WDK - 34002571
- HMNV 6202XK - 34002565
- HVN 6182W5K - 34002585
- HVN 6182X5K - 34002566